I have no doubt they sound great through a guitar cab, in fact I know they do... So does gen I. And so does pretty much any other modeler I have tried into a nice power amp / cab setup. At that point you are basically using it as a very nice preamp with really good fx, but I personally feel you are only getting half the versatility and half the 'story' at that point. Even your time based fx are somewhat compromised because they are being fed before the power amp + cab
I firmly believe the weak(est) points of the POD HD, 11R and GSP1101 are the cab models (the GSP allows third party IRS but only 512 in size and I think that is noticeable and detrimental). I personally feel the very best modelers (really only the AxeFX to be honest) have a chance of holding up really well using frfr. Really well for me means not missing a "real amp" in the slightest.
Firmware 11 really added something extra and special when I had my standard; it seemed to close the gap for me blurring the lines between a real amp (that was sitting 5 feet away from me during AB comparisons) and FRFR (studio monitors). I am going under the assumption that AxeFX II is going to be even more realistic, defined and have almost all of the nuances of a full rig in every aspect. I think those nuances that I'm expecting may get lost if using a traditional power amp plus cab, that is all.
But like I said, to each his or her own and the AxeFX plus power amp and cab is still an incredibly deep and versatile tone machine. To be totally honest I'm considering going back to an AxeFX standard and using studio monitors for recording/low volume and power amp plus cab for live / in the room because I KNOW that will always sound really good. But if I forge ahead with the II it's FRFR or bust.
