My own experience is that it is useful for what it is, but in the end I'm not a real fan.
Downsides include:
- The small form factor. Imagine everyone in the band trying to set up/modify 'their' mix wearing their instruments while crowding around a bowl of M&M's.
- You are at the mercy of everyone else's tweaks to their section. You get a nice balance, then the other guitar playing turns up his 'amp'. Now your mix is hosed and it's back to the bowl.
- It's a massive spaghetti mix of cables by the unit, hard not to step/trip/yank on them, etc.
- You are tethered to a limited range unless you are use long instrument and headphone extension cables (see points 2 & 3 above.)
- Everyone pretty much needs a mic in order to talk to each other, even non-singers.
- Hours in headphones can be less than fun.
On the up side:
- Given use of v-drums, etc., it can be possible to do quiet rehearsals. (As an aside, it's pretty funny to listen to: A bunch of tickety-tickety/whap-whap accompanied by a capella versions of all your favorite songs.)
- Use of JamHub remotes can alleviate some of the downsides listed above, but add $$ to the overall costs.
My preferred solution is in between. I run everything into a Presonus mixer: V-drums, keyboards, direct guitars and bass, vocals, etc. and use a pair of CLR as the PA. The overall level is not much more than playing a CD and the sound quality is killer. Everyone learns to balance their sound within the overall band context rather than a bunch of 'more me/less you' mixes. No ringing (or sweaty) ears, everyone can talk, I have worlds more flexibility using the full mixer (real EQ, compression, multiple FX and so on) plus I can record all 16 channels right into my laptop with pristine quality using their free Capture utility. And if I really want all headphone, I can either tap the main mix into a multi-headphone amp or set up 3 or 4 sub-mixes.
Works for me, my .02.
TT