The reason Survivor has such strong game play is that the pay increases so much more the longer they stay. They fight tooth & nail to stay just another week. BBUS HM fight to make it to jury house, but after that, there isn't much incentive for most of them than to bide time & stay off the radar. I think they thought this 2 HOH would help but it's been a bust.
I really enjoyed BBUS2, every competition/task had a psychological impact on the HM or the game - of course, Dr.Will was Tim caliber entertainment & the show wouldn't have been the same without him.
I've seen almost all the BBAU tasks done previously on BBUK but most have also been perfected by BBAU.
What I think I like most about BBAU is the almost constant interaction with BB. Even having one HM assign duties (cleaning, cooking, baking bread, etc.) and having HM with daily duties.
Having BBAU with live feeds & an unlimited budget would be awesome but otherwise, no thanks.