Dude, you bought behringer!
But seriously, I've seen many bands flog them for a while with no major problems. You should be alright, but I gotta say, a used name brand anything has more resale value than a NIB B-ringer.
Just to rub it in a little more, last year I bought (all used) 2 Carver PT-1800's, 2 PT-2400's, and 2 QSC 1602's mounted in 2 racks all for 1700 bucks. The deals are out there if you look for them. And I was able to test all of these amps out before buying.
Granted the racks are beat to hell, but whaddya want for that price!