Not exactly, I did say that my current receiver and media player are reliable renderers, but I have and have had far more devices which were not reliable to the point that I have decided to not even try.
The thing I took objection to was when you said
UPnP/DLNA is never reliable in my experience.
Which you've just contradicted, but that was the reason for the initial discussion. Ultimately, yes there are bad implementations, but that doesn't make the standard or all the implementations of the standard unreliable because it absolutely can be, and is for the vast majority of people using it.
I don't know what the process/cost/resources are to select reliable equipment
Before I buy a piece of equipment I just check the spec sheet for codec support, then try and find evidence of gapless playback.
Once I have the equipment, the first thing I do is break up a track into 5 second chunks and play it back to check for gapless playback.
Assuming that works I'll generally just put a multi-hour playlist together and leave it playing.
I didn't even manage to test the initial WiiM mini because it wouldn't play from my server, so it went back (after
trying to progress it with support). I tried again 6 months later when I had more time available and managed to track down the problem, but because I'd had no useful support from my first WiiM tickets I sent the second one back too, even though I did have a workaround (to transcode everything). I then got a Pro, WiiM eventually fixed the first problem, then addressed the "poor" (fine for real world use) gapless performance and since then it's been perfect (as a renderer).
but even then the functionality is limited compared with other options.
I'm not going to argue that it's technically as sound as modern alternatives, but - ignoring gimmicky features like Plex sweet fades e.t.c. - it's only really missing multi-room playback, otherwise it's still the preferred mainstream choice for local playback, mainly because the modern alternatives have silly limitations like bit rate (Airplay) and gapless playback (Chromecast) e.t.c.
The other reason that I'm in the UPnP camp is because of the servers, as no other system handles the metadata like good UPnP servers can.
At the end of the day you have to identify what's important to you and pick the option with the fewest other restructions, as there's no perfect solution.