I agree with most of that, however, I think bigger driver of the "lack of improvements" in the piston-GA realm with regard to engine tech is certification costs. I mean, a clean-sheet design would be great an all, but even something as simple as updating to a modern fuel-injection/direct injection setup would have exorbitant certification costs. Engine manufacturers (inlcuding Lyco/Conti) have just about zero reason to put any money into R&D for updates to existing engine models. Even if there were a 10% gain in power/SFC from doing small mods to cylinder design or intake/fuel injection, they wouldn't bother with it because of the immense cost of certification. Hence why Rotax is about the only one who has made modest improvements over the years because their barriers are quite a bit lower in the Experimental realm. I don't think it's that GA is content, it's that there's no other option given that certification costs kill any development that would be possible.