IME that sort of failure occurs when metal topsheet skis are improperly mounted as Robie suggests. Metal topsheet skis must be drilled and tapped (sufficiently deep), lest the screw can create upward forces on the topsheet. The screw needs to thread into the tapped hole without much force, not unlike a machine screw threading into a nut -- maybe a wee bit snugger but not much. I always tap wood core skis too.
I have Sidestashes with Dukes for lift skiing. They are wonderfully versatile skis. But I wouldn't tour on a ski that heavy.
I also have grunge APs (Coombacks) which have very soft cores and, unlike Sidestashes, have no metal top sheet. I helicoiled nearly all the holes in my APs. I've mounted Dynafits on at least 5 Coombacks, all of which had soft cores and required some helicoiling. All those mounts are holding up fine. Light cores require care when mounting. And sometimes helicoiling. That's the price one pays for light touring cores. No biggie. That's why I have a helicoil kit.
ETA: I agree with Rong re Dynafit screws being a bit too short for some skis. If the ski core is thick enough I use a longer ABS, available from Slidewright.
