Our cars go through 2 sets of rears for every set of fronts. Apparently the rears eat up the inner side on the tires due to camber settings. Would it be ok to just adjust camber setting to a a more nuetral value just to increase tire life to say 1 is to 1 rear to front tire consumption? This is for a street driven car with occasional spirited driving. No track work. Will the handling suffer tremendously?

 

The handling will suffer, not "tremendously", but being that it is a sports car, it will lose a bit of its handling characteristics.

In addition, even if you set the camber at 0 on all 4 corners, it will always go through rears faster than fronts. It's a rwd car (I believe the 4/4S is still rear-biased as well) and hence traction/acceleration is exerted on the rear tires.

 

Doing so will reduce tire wear across the tire's tread cap, but not much as a whole. You'll never get these cars to wear front to rear axles 1:1.

 

I would not do that. I believe the car's stock alignment is set up to under steer, unless pushed really hard. This helps keep novice drivers out of trouble when they push their cars hard because understeer is easily controlled by lifting up on the throttle. If you change the rear camber you're going to make the car more prone to oversteer and for a novice in a 911 this is not a good idea. Lift off in an oversteer and you'll find yourself facing the wrong way or worse wrapped around a telephone pole.