Dope,
Age can catch up to athletes very quickly. The last half of the season last year wasn't even average for an NFL QB. The Jets were in great position to win the division, and QB play helped take them out of it. It wasn't just QB play, the Jets D turned south as well, but QB play had a lot to do with it.
I don't think it would hurt the Vikings to take a look at Brett. But it's a bit of a gamble to sign him. If you have a QB spot that you don't mind losing, then I say go for it. How good do you think Booty can become? If you don't think he's ever going to be much, then their may not be much of a downside to losing a QB spot to take a chance on Brett.
I believe GB did the right thing going with Rodgers after watching Brett in those cold/bad weather games. Oh, he can still handle the snow, but cold is another story. So I think Brett, and GB would have been in trouble keeping Brett in GB when games can mean the most, at the end of the season. You guys might not have to worry about that as much, unless you have away games in cold weather cities in December.