It's not about price.
It's not about "tier."
And the possibilities of having something that works versus something that outright doesn't work is skewed much more in-favor than it is against, simply because of the overall tolerances of the system.
The "does it run?" or "run it" mentality really isn't the right way to go about answering this kind of question, because we've seen time and again that the odds are overwhelmingly in favor of "the adult LEGO" to do just fine.
Rather, this is simply about understanding where there
may be problems, and understanding what is actually going on when those problems manifest, whether it be out-of-the-box issues or only manifest upon harsh use (or even abuse).
This is specifically why I chose to showcase those particular SOTAR videos - I specifically picked instances where Albrecht had the chance to pursue what folks would consider to be "higher-end" components, ones which are in the pricier end of the market, demanding premiums that are typically above (if not far above) "lesser" counterparts.
The reality is that we all exist as that unique
n of 1 sample. As-such, it's on-us to vet our individual weapons. Look at that one Sandcutter BCG that refused to run and had a broken gas key fastener? And towards
@10mmLife 's post above, I can draw a personal example - my BCM:Battle Arms Development/upper:lower (billet) combo fits with noticeable play, whereas my Aero does not; yet of the two that BCM holds noticeably tighter groups.
Understanding that there are differences in materials, build quality, QA/QC, as well as the possibility of tolerance stacking with even the best components - this isn't meant to disparage a home-build using less-costly and supposedly "lesser" components or to somehow extol supposed merits of magical unobtanium that one had to trade their firstborn for. This is about understanding how the system is supposed to work so that we can better understand how to address the problems that inevitably arise.
Look at it this way, with everything else equal, who would I pick for a partner in a class?
A shooter who brought in a cosmetically beat-to-hell self-built PSA, with SOTAR videos in his YouTube Watch History and who's breakfast table-chatter is about the difference his gun groups with one ammo versus another....
Or a shooter who is unpacking his fresh-from-the-store Knights SR15, with a phone full of sexy gun-bunny pictures and who talks only of the latest and greatest gear.....
I'm betting that when my gun goes down, that first guy is more likely to be the one who pulls a BEV Block and a portable hitch vise out of his truck.