I've had an angle gear strip a tooth, but have usually only come across stripped splines in the angle gear side of the coupling sleeve. I think a coupling made of swiss cheese together with excessive clearance on the angle drive splines leaves very little bearing surface under load. The other 2 x V8s I play with have noticeable wear on their splines as well, but don't chew out the new sleeves I've installed like mine does. I had thought that the pressure sensor in my Haldex could be providing too much grip on take-off but I've changed the pressure sensor and serviced the Haldex again. The pressure sensor was uprated from 4 something or others to 8 (all you can buy now).
If you partially lock up the Haldex (ie "Instant Traction") and take off on full lock often in the city then I think the torque applied to a weakened /worn / sloppy spline is what kills them. The transmission splines are a much closer fit and never seem to wear at all.
If I have the angle drive out at some time I'll look at welding it as an experiment (since I have a good Haldex and prop shaft at quite some expense) but I clocked over 456789km last week and I'm not pulling it apart just for the fun of it.
