netmusicians.org - the guitar gear mp3 database
This guy is from HCAF, and he posted a couple mp3's from a Fender Prosonic and a VHT Deliverance. The clips sound pretty good; definitely better to my ears than any of the Grendel clips I've heard. For $330, it's a steal, even if you plan on swapping the speaker.
It's a little tough for me to evaluate because those aren't sounds I would normally use, but I definitely hear the "boxiness" that you get with iso cabs, even the Grendel. I've gotten better sounds with the Grendel than that, but I had to work at getting the right mic and mucking around with mic positioning and post-EQ.
For that price, it's probably worth experimenting with it, though.