I've seen and shot (and took a carbine class) with cheap short uppers and never had a problem. PSA 11.5" 5.56; radical firearms 300blk in 8.5" and 10.5" and radical 5.56 10.5". All 4 run perfect suppressed or not with cheap BCGs and standard buffers. I'm going to keep knocking on wood before I ever buy a different buffer but I would like to shoot someone's super expensive tricked out gun to see if there is a noticeable difference in recoil or something?
I've always had to tweak it a little bit; usually just a heavier buffer to slow the bolt down. Other times I've had to play around with the gas port or BCG. That's awesome that you haven't had any problems and I hope it continues for you. I've seen guys run some of the cheaper stuff through really tough carbine classes/training sessions. Sometimes there's no issues. Sometimes we're full on armorer mode replacing parts in the field when we should be shooting. Not too long ago a guy busted his buffer tube on his cheap lower build while running a drill. Another time the gas key wobbled off the guys cheap BCG because it wasn't properly pinned; in fact, it may not have been at all. I've only seen these problems with cheap builds. Just my humble opinion.