In the past 4 months I've managed to destroy 3 differentials. The last time it took my gears with it. To get the car back on the road quickly, I had to install 3.42s.
For you guys that wonder what gear you should get with an m6, most definitely get at least a 4.10 gear. Driveability is night and day better when compared to the 3.42s.

 

I'm considering doing the swap from 3.42 to 4.10 in my m6 car. How's the traction with street tires?

 

no traction in 1st for me, 2nd spins pretty good too, but it sure is fun. Pulls hard.