I think the first question is, how much money are you okay spending?
The second question is, how do you want to power it?
Around these parts (where we apparently love regulation...), it's illegal to have a tank of gas in your home. Regardless of legality, I am not a fan of having a tank in my house. So instead of having a propane tank, you could plumb in a natural gas line to your roasting area which you could hook up to a gas roaster (as I believe
@jammin has done). The reason I mention this is because the Commorant and a few other profile-esque roasters require gas, whether it's natural gas service within your house or a propane tank. If you're going to roast in a shed or garage, that should be a piece of cake. But not all of us can do that (we've had a cold winter in Chicago).
I thought about it a lot and decided not to have a natural gas line run for my roaster into my roasting room because I don't know how much longer I'll live here. Instead I went with the Bullet because you can plug it into any 110v outlet and boom - you're roasting. Actually, it requires less energy than a Behmor due to the infrared heating system. If you care enough to look at how much it costs to operate it, Aillio has performed studies and proven that it's the least costly roaster there is (gas and electric included).
I roast 1lb at a time and can EASILY roast 4lbs an hour at that rate. It's rated for up to 2.2 lbs/charge, some people do 2.5 lbs. You could roast 8-10 lbs an hour on the roaster without too much heartache. The only real drawback is I give it a good 40-60 mins to heat up. It will be "ready" in about 15 to 20 mins, but if you want the roaster to really be preheated and ready to go, it takes 40+ minutes. That really isn't a big deal though, because once you get going it's a matter of charging the roaster, roasting about 9 mins or whatever, dropping the beans, giving it about 4 mins to be ready for the next batch (while the latest roast cools simultaneously), and then charging again. Repeat. Like I said, 15 minutes per batch from charge to cool and charging the next batch.
Finally, and this is going to be true of anything, it helps if you have some understanding of how things work. Brewers seem to get this naturally, but I'm astonished how many people on the roasting FB pages can't understand basic how-to items. So, you see a lot of people complaining "I don't know how to tighten the belt...wahhhh". Freaking crap - turn a screw, dude. Every roaster that has moving parts (including whirley pops!) will have issues from time to time and you'll have to figure it out but that should not be a surprise to anyone (yet somehow it is). /end rant
So, basically if you are okay dropping $2700 it's a fun roaster and will keep you busy. If you don't like learning new things and trying new things when it comes to roasting and profiles and whatnot, and making occasional basic repairs - it's probably not something you'd benefit from. But there are tons of different settings you can mess with (drum speed, power, and fan speed) that can change your roast in a variety of different ways - which can be fun or frustrating depending on the day.
If you get one, I'd suggest going through SM's because there's no import duties and sales tax depending on where you live.