I'm using the Aqua GFX blocks on my 7950 which are just great. I havent overclocked my card however as this is running on my mission critical system and I just havent played yet, but temps are pretty reasonable I would say, in the 40's idle. (the cards tend to run hotter than the 7900's).
As for redundancy I'm not 100% the G80's will feature a new reference design. If they do then then I'm sure in due course you will see price reductions.