Look man.....I'm a newbie to the forum kinda....just joined but I think I can field this one.
I just got done building a pretty nice 1 BBL system and I could probably steer you where I think you're heading.
Budget aside....it just makes sense if you're going to brew a lot of beer consistently to jump up to bigger batches. A lot of homebrewers give me flack for putting a BBL system together....but here's my pitch....
* (1) 16 hour brewday accomplishes the same mission as (6) 8 hour brewdays. Well now....that's 32 hours of savings.....that's almost a whole freakin weeks worth of work.
* With scale comes a little bit of cost savings. You're mash efficiency will likely increase if you put some thought into your system and you will use less consumables like sanitizer and the like. And a few other things that can be discussed later if you like.
* You always make enough beer at one time that the majority of it actually gets to age to perfection before you and all your greedy little buddies drink it all up.
* Last but not least.....If you design your system as large as possible without losing control and blowing all your dough......you can actually pay off the equipment in say 3-6 years somewhere in cost savings vs buying cheap chitty beer. Of course that depends on how much you drink and also how much you're losing to friends and family along the way. However, for me it was more about time savings than money.....but then again I'm as cheap as they come as long it don't affect the finished product or create a lot of extra work......I'm not proud....if my system is a little ugly....who cares....she gets er done.
Drawbacks to a big ole system.
* cost and justification thereof....had to throw it right out there.
* space. You need alot of space to do this right. I barely have enough room in my basement and its pretty good sized. I'm actually real happy with my setup but a little more room wouldn't hurt. Plus now that space is accounted for permanently. I can't really use it for storage or anything, but, you know you can always get a storage shed on sale and slap it in the back yard.
* plumbing and the like.......you gotta make sure to do quality, tested, double checked work in the house where you and your family live if that's where you brew. Be extra special carful with gas lines and placement of burners. Don't be afraid to buy some sheet metal and go crazy cutting up a million heat sheilds....you won't regret it. Also consider ventillation if you're gonna need it. I just brew in the winter now, I live in the Midwest, and I get away with just keeping the basement door closed and cracking one window and it stays confortable enough I'm not burning up and I'm also not suffocating myself. Another advantage of NG is that it burns cleaner than propane and you're less likely to produce too much carbon monoxide and asfixiate yourself or your sleeping family. Although electric would be nice actually in a a lot of ways.....but I'm already committed to my way of life here. That said, I don't know how you're going to boil.....electric, propane, or natural gas......but I highly reccomend NG if you can swing it. Although I don't know that much about brewing electric so...........you might want to read up on that depending on your situation
* I'll sum things up here and get to the point after this. Most people who critisize my system do so because they feel that it limits the variety of the types of beer that you can brew. Granted.....doing 5 gal at a time you can really do a totally dif beer every time you brew. That's great if you don't know what you like to drink yet or you just like to mix it up all the time. But check this out.......you can start out with a 31 gal basemalt only mash and end up with an IPA, a pale ale, a lager, and a Kolsh all in one big ass brew. You just have to juggle around some dif yeast strains and steep some specialty grains instead of throwing them in on the mash. It also helps to have extra boil kettles and the like. What I do is if I want to go crazy on variety I do a base only mash and then split my collected wort between the BK and the HLT. My BK, HLT, and MT are all the same size (40 gal). My system is real freakin tight though. No wiggle room hardly at all. After that you can change the malt profile to a great degree by steeping and you can get two completely dif hop profiles. Then all you have to do is have all your appropriate yeast strains ready and you're in like flint. You could even throw a third kettle in on the mix like your old reliable keggles
Just all depends on what you've got in mind.
Now, all that said....you need to decide what size system you think would suit your needs for good. No more major upgrades. I know I know I say that now........lol
As far as quip goes....you're not doing bad so far but somewhere along the lines you should IMO at least think about doing away with your keggles. Not that they're not useful and convenient, (dont get rid of em till you're sure you don't need em) but if you want to do 15 gallon batches or even bigger......they aint gonna cut it. I reccommend finding you some SS stock pots on ebay or something for the right price, drill a few holes and take em to the local welder. You won't regret it. Then you can really fine tune and customize your batch size. Just be careful. I ordered 3 supposedly 45 gallon stock pots and they ended up being only 40 gal. They were made in China.....go figure. If I hadn't put a lot of thought into my process and aired on the side of caution.....I would have gotten screwed on the deal......as it stands......everything worked out ok except my BK is just a little undersized. I have three choices.....I can either drop to 25 gallon batches, buy a bigger BK, or just add a little make up water at the end. I know it sux to have to do this with such a nice system but.......I chose to pressure can some make up water and be done with it.
Now as far as your worries about false bottoms and dip tubes and filters and all the rest of that stuff......well...... be prepared to do your homework before you build.......there's a lot of info out there to absorb.....but its hard to find sometimes......and you need to understand some basic math and use your head to design a good system. With that said.....I use a very simple slotted manifold. I'm the FNG here so I don't know how to use the site yet and provide pics and the like, but there's pics out there on what a manifold looks like you just need to make one that fits your system. Or go with a false bottom if you want I hear people do ok with them too. Its all about preference sometimes and how anal you are on chasing effieceincy. If you get your process down right, you should be able to make things economical enough that efficency becomes less of an issue. Here are my cardinal rules when it comes to my brewery. If its cheap and works go for it, if its dirty......clean it now now now!!!!!!!, if it looks like a shotty idea it definitely is, If a few experienced brewers in a couple different places agree that it works......its a pretty safe bet. The inverse of that last on is also a safe bet. If you hear a few people talk chit about one particular method or process, it probably is not worth doing unless you're smart enough to figure out the shorcummings, in which case pass along that info us if you please. It's not rocket science. For my dip tubes I put the holes on the kettles as close to the bottom as I could and still leave room for the welder to work. slap on a ss compression fitting and home sweat or plumber help dip tube and you're in business. As far as a filter goes, which you didn't inquire about but you will.....I use the standard chore boy ss scratchie pad. It should do you fine if you don't use pellet hops or if you are willing to use a hop bag in the boil. I use whole hops exclusively and home grown to boot. If you put as much as 4-6 oz of pellets in the boil you will likely clog your filter. There's not a lot of good reading that makes you feel confident out there on reliable filters......you just gotta pick a route and go with it and trouble shoot later if you have to.
Well hopefully this steers you in the direction you wanted.....if you want to pick my brain feel free.
Cheers - Shaggy