I’m still in the process of figuring out how this Abstract Profile section works to be honest, but I already noticed 2 cases where it is rather powerful.
The one that is probably going to be used most: Lifting shadows without blowing your highlights and/or increasing noise (to a degree). The only part you need for this is the top part using custom, no need to adjust the Custom Primaries section.
This might introduce other things that need to be adjusted, but there’s a link between Abstract Profile section and the CIEcam module. They seem to be going hand-in-hand.
There’s the Sunset in Corsica image floating around atm that’s giving people, mainly noise, problems. I’ve been experimenting with that image a bit and the Abstract Profile section. It does a good job in keeping the noise and otherwise blown out sky under control (here’s the pp3 from that ongoing experiment: sunset.in.corsica_1.rw2.pp3)
Coming back to the above mentioned OOG problem: You can use the Custom Primaries section (set to Custom) to tackle this. As of yet I’m not entirely sure how this translates to sRGB when creating the final result. It all seems to work on my monitors (a good one that’s calibrated and a uncalibrated mediocre one). Both show a subtle, in my opinion pleasing, difference in the pink sweater. It certainly doesn’t show as OOG any longer in RT.
Here are 2 basic edits (my base profile + slight Film-like Tone curve + Abstract Profile + CIEcam only):
And this is with Abstract Profile turned off:
I downscaled the images after the fact, so I’m not sure if the nuances are visible, so here’s the sidecar I used.
EDIT: Just checked and it is visible.
EDIT2: Forgot to mention this but I did use Auto-matched camera profile and Base table in the above edit. This 'cause that is what @stefan.chirila seems to prefer and is relevant to this topic. I would not use this myself.