I use the same amps, Laney GH series, and I can nail the tone. They do use Boss GT-3 pedals for all the guitar sound and the laney is really just a power amp, but the way things are setup the pedal is basically distorting the laney anyway so either way it is damn close. Just more versatility with the pedal.
I wouldn't try to copy their gear though, I had the exact same equipment (but no PRS) and had better luck getting the tone straight from the amp then with the GT-3.
For what you want i'd try a laney vh100 for the two channels. That is the only annoyance with my GH in that I have to roll back the guitar volume to get a better clean tone, and I cant set different eq settings. Same amp though, same distortion and it sounds great for most metal without any help. Could try a peavy 5150 too, gets that melodic death sound perfectly...maybe a peavy XXX as well.
you asked what would I use if I got the chance? Engl Powerball with a Bogner 4x12 = Divine.