Yeah built in cab sims, i tested a lot of impulses and i ended up liking the this amp + cab better. Need to do more testing with IR but i want to get best i can without the need of loading 4 instances of an impulse loader.
You should try printing the tracks if you're happy with the sound. It'll save you a ton of CPU usage. I'm a pretty big fan of the Catharsis SPresHigh impulse through Mellowmuse IR1A. That usually DESTROYS the built in cabs in POD Farm.