Drilling through the blade is not as good idea. Once you do that, you have introduced a serious weak point in the blade, and risk breakage of the blade in that area. It's actually happened to many people over the last 12 years in this hobby, and the best practice is actually the tension fit of a single set screw. If you've stripped the threads, you're tightening it too tight. To fix your blade screw problem, all you need to do is drill and tap for a slightly larger set screw and just snug the screw when tightening.