Originally Posted by Air Supply
If you guys had to chose, which would you buy?
Personally, Yamaha. But that's just me being ornery about Behringer copying the EP design from QSC... it's a terrific design for sub duty. That said, I don't run either one - I have a QSC RMX-1850HD, which is the very design copied by the EP (actually the RMX-2450 would be the equivalent).
That said, the EP2500/4000 and my RMX do not have the variable speed fan controller the Yamaha does. If you find the fan noise objectionable, you'll have to either fanmod it or run it in another room as I do.
I should also mention I've never tried the Yammie in person. I've had experience with their gear, but not this particular amp line. Not exactly sure how it does below 20Hz compared to the RMX design.