THe thread with the guy runnign it at .5 daily is the "20.1 vs kicker 2500 vs orion 2500D" thread that might help, I have no expereince with that amp personally.
I have posted this in 2 other threads today so now ill make it 3! YES you can run the 2500 at 1 ohm. I actually ran both of mine at .7 daily for over a year with no problems at all. At .5 ohm the amp will work but it is very tempermental and will go into protect. Also when the test was done between the orion, IA, and Kicker it was one of my amps that was used for the test