Re: Peavey Revalver 4?
In 3.5 you could put any piece of gear anywhere in the chain. In 4.0 they have specific locations for pedals, amps, and post FX. They eliminated the separate preamp and poweramp models, so if you were patching together sounds that way (like me) you'd be disappointed with 4.0.
Sorry, but I like putting an EQ and chorus in the effects loop. pre-4.0 Revalver was the only amp sim that let you do that. (Yes, there are a few other sims that let you disable sections of the amp and you can load the plugin twice with other effects in between but Revalver was much more seamless.)