If you are interested in going all grain...just GO! I know a few people that NEVER did extract batches and their beer is great. You need to make sure to read and reread some good books on all grain brewing until you are comfortable with the process. After that, it's really just buying the correct equipment for the Mash/Lauter process. If you like taking your time and crafting a delicious beverage, and at the same time learning how to make beer in the traditional way, all grain brewing is the way to go.
I brewed 5-6 batches of extract before jumping into all grain brewing. It was an easy transition, and only cost me $25 to upgrade from my extract setup. I took an old 5g cooler, and put in a ball valve and SS braid for the lautering "manifold". I already used a turkey fryer kit for my boil kettle, and for all-grain I simply forced it to do double duty as my hot liquor tank (HLT). I used my bottling bucket to collect the first runnings from the mash, then transfered those to the boil kettle after I had made my last sparge water addition. From that point forward, it's just like extract...boil->hops->chill->pitch.
Braid:
It's coming up to a year since I brewed my first batch, and I've moved on to 10 gallons batches and am loving it. Buying a grain mill with some fellow brewers was the best purchase I've made. Coupled with buying bulk 50# bags of grain for $30-45/bag is a real pleasure. I can now brew a 10 gallon batch of my house ale for $18.93 for the ingredients. Even for my more expensive recipe it rarely gets above $30 for a 10 gallon batch. With extract I was paying $28-35 for a 5 gallon batch. All grain works for me, and sounds like it would work for you too. It's a bit of a step up in equipment, but it allows more flexibility with recipe formulation, better beer(given good process), and it's cheaper per batch.
The three biggest cons I see with all grain are:
1) $$$ for equipment, but this depends a lot upon YOU. You can go and buy an 1/2 barrel automated setup for $6500, or spend a modest $50-100 for a nice 5 gallon system.
2) Time. Extract is faster because you don't have to heat sparge water or perform a 60-90 minute mash and sparge. But if you like brewing, and like taking your time with makin beer, this is a non-issue.
3) Space. Again, this depends a lot on you and whether you brew inside, outside or in the garage. Many people do all grain on their stovetops, but this would never work for me, or I should say SWMBO. Lucky for me I've got a garage I can take over with my brewing equipment.
Well that's got to be my longest post evar! Hopefully you can glean some information from it, and make an informed decision about your brewing future. Cheers to you, and cheers to all homebrewers!