The real downside to SMR drives is "random" writes; adjacent tracks need to be re-written, and then their adjacent tracks, and that keeps going until the tracks adjacent to a write happen to be empty. It doesn't matter much for long sequential writes (because adjacent tracks will be overwritten anyway). I think the re-writing process also hurts read performance for the host, but reads alone don't cause rewriting.

If you need to reshape/resilver your array (grow, shrink, or change geometry), it'll probably take weeks or months with an SMR drive compared to days for a CMR drive.

Yeah, SMR is fine for read. And for most homelabs, I'd guess it would be fine. SMR would be a bastard in a high read/write scenario like in an enterprise. But I think all the Red Plus and Red Pros are all CMR now. Only the base Reds have SMR from the sample I took.

I got burned by WD's secret SMR drives in my home NAS and they sucked! They were marketed as NAS drives, but the performance was abominable, the failed sector count grew steadily from day 1 and it felt like they failed 1 early. Once the whole sordid fiasco came to light I switched to Seagate CMR drives and everything has been mostly OK since then.