Reply to Anyone have experience with Alto and Yorkville subwoofers?

Went to guitar center today with a friend to listen to speakers and I fell in love with the Alto ts112a http://www.musiciansfriend.com/pro-a...-2-way-speaker active 12's. They wanted $275, but I'm going to try and get them for $250.

They had a set of 400w rms passive Alto 18's that they wanted $300 for each. There were not any other 18's in that price range to compare, but I've been told the yorkvilles are very nice. I forget the exact model of the alto's they had, and I was not able to find the same ones online, so I believe they may be obsolete. The ones I keep seeing look way different.

The reason I want passive subs is because they are half the cost and I already have two 450w rms amps and a minidsp processor that I want to use to cover the crossovers and eqing. I noticed that these subs have built in passive crossovers and are meant to be connected to the tops. Would I be ok to bypass those passive crossovers as far as impedance and sound since I'm setting my high and low pass filters with the minidsp?

i've read that cheaper 18's tend to sound boomy and that 15's would be a smaller and better sounding option. Is the lower extension of the 18's worth it for heavy bass music like low dubstep lfo wobbles?