http://www.talkbass.com/index.php?threads/1079812/ See if I can get some more action from this side. Lol
Check out Lync's posts in the Fender Rumble Club. That will answer most of your questions. http://www.talkbass.com/threads/fender-rumble-club.970397/page-38
I thought I read in a thread here just the opposite - that Jeff and the guys had nothing to do with the new Rumble series. I could be mistaken. My 100 watt v3 is due here Thursday - I'll post some thoughts when I have a chance to work it out a little.
Dave Lewis is the principal engineer at Fender, and he was heavily involved from the very begining designing Rumbles from 2003 forward. No one from Genz Benz was involved from what I have been told.