I gotta say I agree with Kris on this one.

If you're aiming at a jazz or country gig then you dont really need a huge kit in general. Different sounds can be achieved with one tom by exciting a range of harmonic frequencies, usually achieved by hitting off centre, pulling the stick back etc. Also people don't expect such a range of cymbal sounds. A large kit is occasionally seen as trying to steal the spotlight.

If you're a thrash metal / black metal drummer looking shin melting double bass and earth shattering toms then more drums are usually useful. It's very hard to match the energy of the fundamental frequency on any tom. For this reason a range of toms can give the sound more oomph. Also by using the different sound of each tom you can get that "running down a corridor of drums" effect my metal guitarist loves so much.

I drum for a few bands right now and the size of my kit depends completely on the style of the songs. In my case I find that elaborate drums are more easily produced on a bigger kit.

Having said all that, the biggest kit I use is a 5 peice with 5 cymbals and a double bass pedal.