Much of the intended improvements and the apparent results of his intended improvements that the OP mentioned in that linked thread are why I do not screw around with the internals of my firearms by trying to make them better than original. I will repair things that are busted (like an ejector) or worn out (like springs) when I have good instructions on how to do the job but that is just about it for internal fiddling. I may go a bit further with a Glock but I was an Advanced Glock Armorer so am more comfortable working on them; still - I'd only use original Glock parts. The only other things I usually will do to a gun to improve it is to change the grips, add glass, or maybe add some other type of sight. Oh yeah, I also have refinished some stocks and made them look better than original but changed nothing about how they fit or function.
ETA just passing on the link. Do with it what you will but I suggest copious research.