Is this the mixer you are talking about? http://www.musiciansfriend.com/pro-audio/yamaha-emx5014c-14-input-stereo-powered-mixer. In my band 8 mic channels isn't near enough. For a little more money you could get one of these http://www.musiciansfriend.com/pro-audio/peavey-16fx-16-channel-mixer-with-effects It has more channels,31band EQ or 7 band parametric, a crossover and semi parametric mid EQ. It also can support 4 seperate monitor mixes. Way better board IMO.
Have you heard one ? My Yam also has sweepable mid. The 31 band would be nice. I use externals, dual 15's as for me that is generally adequeate. THe Yam is also powered withy 500/side into 4 ohms ... The 5014 is available in a 16 ch version as well... When mixing other bands and needing more channels, I used a separate mixer off to the side and brought it an Aux in.
There's a lot of ways to skin the cat. The Yamaha 'pro-sumer' class mixer is one. Maybe not for everybody but it certainly shouldn't be discounted just because it is powered. Sound quality wise it will hang with much more expensive boards... personally I'm close to done carry external racks of stuff. I want in, seyup, play and out with a minimum of fuss and I want all the tasks to be easily spun out to other folks willing and capable of helping. Which is why I went the Presonus/QSC route and spent the coin to do so. The Yam I still respect for what it is and keep it in my rental inventory.
I also have a presonus 16.4.2 and a soundcraft LX7ii. When I need more channels I bring enough board for the gig. BTW that Peavey board i mentioned earlier in the thread I picked up used for $299.00. It feature set is way superior than the yamaha you're talking about.