I dunno man... while I can see where you're coming from, I kinda side with the OP here.
Whether or not the extra holes make a big difference, they do make some difference, and that's not something the OP could reasonably have expected when dropping his skis off for a professional mount. It's different when someone gets their skis remounted, you know you're going to come out with some extra holes... but if you'd gone in to get them mounted and they had said sure, but you'll have an extra set of filled holes up the front, you would tell them to get lost.
I once took a pair of skis in to get mounted and by some fluke they had another pair of skis the same as mine but a different length in there at the same time, and our bindings got mixed up and I ended up with some Marker bindings instead of the Looks I expected... the shop then offered:
-Take them as they are, and we'll refund you the difference between the Look and the Marker
-We'll give you a new pair of skis, with the Looks
-We'll remount with the Looks and give you a $100 refund on them, and not charge you for the mount.
I took the last option... I thought the shop handled it very well and went away happy. Personally I think OPs shop should be offering him the second 2 options or similar as well.
True, I suppose it depends if they seated the thread properly first... I was always taught the method mechanics use, where you turn the screw anticlockwise until it 'drops' into the top of the thread so you never crossthread. If they crossthreaded it then yeah, there's going to be a pretty good chance of them ripping out.
And I think FKS ripping out is more to do with the type of people who ride them than the bindings themselves, although thats just my take on it.
You make a very, very good point...
More power to you OP! As long as you came out happy and the skis hold up then all's well that ends well.