After reading the nearly 1000 post thread on this ROM I did the deed, carefully following what has to be one of the best guides I have ever seen. Up and running, rooted JB stock VRZBLK3 with an unlocked bootloader and Clockworkmod Touch Recovery.
And the "No Wipe" style is the first I have seen, but it makes absolute sense to me. If Verizon can push us a whole new OS version (JB) and not make us lose our apps and data, why couldn't a dev do it too? He did, and with spectacular results. It seems more fluid as things open and close and definitely more peppy than stock rooted ICS.
I asked if it would be a simple matter to flash a previous ICS rooted nandroid if I wanted to reverse my tracks on this ROM and he said it would absolutely work to do that. The guide is written well enough for even flash-newbs like me, and covers everything. Just follow the steps to the letter. Couldn't be much easier, considering it appears there is no one click root at this time for JB.
Cool beans!