I made a thread a couple days ago on sevenstring and it's all about isolation cabinets. Here's a link, hopefully I can get more feedback on this forum.
Ehhh... The Silent Sister's got the right idea, but they're forgetting that it's not just the speaker and mic placement that get tone. The bleed from the other speakers, the wood the cabinet's made out of, etc. all have a big effect on it. While this is a really cool idea, i think it's a bit limiting and who's to say how hard it would be to swap out the speakers if you wanted something other than a C75?
The other thing that bugs me is the $1000 price tag. Why not just get a power soak/hotplate/whatever? Cheaper, you can use whatever cab you want, relatively quiet, and it's a true open environment.