So what do you all think of "MIPS" technology? The concept makes good sense to me, but how well it's actually been implemented and real-world results are pretty much an unknown at this point.

I had to Google it to see what it was, and yes the concept seems logical to me, reducing rotational forcing when the end of the helmet but first and can cause a neck forcing injury, well that's my take on it.

I see this has simply another step in incremental gains and understanding of force dispersion etc etc. Look at motorsport, which I've followed closely for 35 years, helmets are much lighter than before, reducing the forward force in accidents, devices like the HANS device has gone a long way to reducing fatal and serious neck injuries, cars themselves are designed to disperse energy with crumple zones etc that has clearly tricked down to regular cars and the overall advances in safety of regular cars.
It's all incremental, and any good idea in bike helmets will trickle down to affordable models, case in point is the retention system with ratchet that holds a helmet in a proper position and keeps it there after an initial impact.

So for me, this concept is great, one more advancement.

That's where I started, but $22 Bell helmets are not shaped like my skull.

The manufacturers are pushing it, but as you say there's no independent confirmation that it's a truly worthwhile thing. At least one independent helmet organization that's not trying to sell anything seems to be unimpressed.

OTOH, the Bell Tempo/Draft MIPS helmets are down to $35USD+shipping, and other things being equal at that street price point there doesn't seem to be any particular downside to buying in.