Well, further adventures with the #OCLP iMac running Sequoia are promising. It's settled down now iCloud indexing has finished (medianalysisd and suggestd were hammering it).

I've installed Lightroom on it; there's a little graphical corruption every now and again, but it disappears after a second or two.

Lightroom Classic, sadly (as it's what I really wanted to use on this machine), crashes every time I launch it. v15 is incompatible (won't let me install it), and 14 and 14.0.1 crash. Suspect this is because of GPU shenanigans. Ah well, another reason to learn Darktable 🤷‍♂️
Ah, result, Lightroom Classic 13 seems to work perfectly on #OCLP Seqouia with it's crappy Kepler GFX chip 👍
@WiteWulf I looked at Darktable earlier today because it has a negative conversion module but man it's an odd UX to get your head around, I gave up in the end.

@matt303 100%, the UI/UX is its biggest weakness. It’s got the classic “UI designed by programmers” feel to it 😆

Each time I’ve tried to learn it it’s felt like it’s fighting me. But those who have spent the time getting to grips with it say it’s every bit as powerful as Lightroom, just a really steep learning curve.