I've encountered 2 separate issues with my flowflex binding installation whenever I've removed and replaced the bindings on the plate:
1. The existing holes in the bindings are (I believe) too small for the screws, so you end up with the phenomenon where the screw cuts threads both in the plate and in the binding, so that you can end up in a situation like the one in the picture earlier in this thread because the screw head has screwed itself as far as it can into the binding but hasn't gotten all the way into the ski yet. I don't know if there is a technical reason for the holes in the binding being so tight, but I just drilled those holes out to the actual outside diameter of the screw (the material is plastic) so that the screws could go through the binding without any resistance. This made a 100% difference in the "feel" whenever I'm installing the bindings because I know that all of the resistance that I feel is in the actual plate and I can tell when the screw is tight enough.
2. The screw length can be a possible problem--there are different length screws for different hole locations (at least that's what I've got with my '07-'08 Cold Heat with RXZ-13) (in my case, the front screws in the toepiece are the longest (and in my case, have a slightly smaller diameter head), the back screws in the toepiece and the front screws in the heelpiece are the shortest, and the rear screws in the heelpiece need to be somewhere between those; my problem when I got the skis was that there weren't any screws that seemed the appropriate for the rear of the heelpiece as the screws only stuck out about 2MM from the bottom of the binding; I replaced these with longer screws that I ground to the length needed to get maximum depth in the plate). I think it's important to go to the trouble of doing a dry run with your screws (putting all of the screws into the binding and looking at how far they all stick out) to make sure that you've got the right ones in the right holes (they can't stick out more than 4MM from the bottom of the binding as that's the maximum screw depth per Fischer, but obviously you would want to have close to maximum depth for each screw to get maximum thread purchase and to minimize the possiblity of the screw stripping out).