That's the problem with flat head screws, the Allen key size is small relative to the thread size. I'm right there with ya, I've stripped everything out except for the Quick-Loc and the accessory screws since those all use 4mm Allen keys. The 2.5mm and 3mm head screws all get stripped quite easily.
I have bins of metric screws from all the AI related stuff I've been working on, so any time I take a screw out, I chuck it and replace it with a new one. Cheap insurance to help avoid it getting stripped out.
Yup, countersunk stuff can be a pain in the butt. I've dealt with a TON of super small stuff on RC Cars over the years and honestly, it's not the screws that are the problem its cheapo Allen wrenches that round-off and then screw up the hex on the screw. If you deal with a lot of them a good set of hex drivers is well worth the money IMO
These are the best I've seen, they make them for the smaller size up to 3mm I think?
MIP Gen 2 Hex Driver (3.0mm) [MIP9211]
Same Iconic Look, Boosted Quality & Performance! For over 30 years, MIP tools have been the go-to gear for RC enthusiasts who demand the best. The... MIP9211
www.amainhobbies.com
Jake