you know putting winter tires on just the rear wheels is pretty stupid right?I got my G37 in AWD form and semi-regret it. Since I rarely end up driving it in the snow, 90% of the time Im just carting around extra weight (for less mpg, slightly less performance). The thing that gets me is how much it feels like the front end wants to "push", presumably because of the extra weight.
If I were to do it all over again, I would get RWD and a spare set of rear wheels with Blizzaks. If I were to buy a car for my wife, she would get AWD.
As far as 5.4 vs 5.1 second 0-60, around here it would make just about zero difference. The car (even in AWD) is so fast that by the time I accelerated up to 60 I would be on someone else's tail. To me its just nice knowing what it can do, and have fun throwing it through the turns regardless of how fast I can get to 60 mph.
Many people with AWD forget that their 4 tires stop no better than the other guys' 4 tires. Yes, AWD will get you going, but you still see plenty of them in highway ditches.I wouldn't recommend this approach. It will get you going, but won't help you stopping. Get all 4.
Tire Rack Tire Test - Winter Tires: Mixed vs. Matched Tires - YouTube