A lot depends on the KIND of music you play, the kind of people you are playing FOR, and the VOLUME you are playing at (or ever expect to).

It's all well and good to look at a couple of guitarists with too much gear (they MIGHT be used to bigger rooms), but every time you bring an arranger to a gig, well, you just walked in with a drummer and bass player, and a couple of guitarists too....! You try to do this gig with too LITTLE gear, and you sound thin, brittle and small.

Now, if this is what your audience would prefer, you're in business. But if you went in to the gig saying you could sound like a full band, you'd better have the PA to produce this. 10" top speakers (with a horn or tweeter) are actually not too bad, but ONLY if you reinforce them with a sub. Doesn't have to be that big (12" or 15" tops, self powered), but unless you put a bit of 'oomph' into the room, you are going to sound like a bad Muzak system, and basically negate any advantage the arranger gave you.

And, don't forget, you are not buying your PA for the smallest room you play, you are buying it for the BIGGEST room you are likely to play (or you have to hire a PA for those gigs). So don't go TOO small.......