We need to separate out a few things:
- Decoding: All renders should be identical on this, EVR, JRVR, madVR - it does not matter
- Scaling Luma/Chroma: Where do you want this be done? You have three options, either have the HTPC do the initial scaling to your target Luma resolution (and corresponding 4:2:0 to 4:4:4 for Chroma) or use profiles in madVR (and upcoming) / JRVR to output native resolution for the Lumagen to then do the scaling... and finally just let the display device do it. Each renderer (madVR, JRVR, Lumagen, Display Device) has their own features, scalers, enhancer etc etc. They will be a matter of preference and none will be "correct" as they all are inventing information that does not exist but is extrapolated from the input for the final display.
- Tone Mapping: If you have a colour space that needs mapping from Source to Display, then where do you want this done? The options are HTPC (madVR, JRVR), Lumagen, or the Display Device itself.... or even some combination of all three.
Typically, the Display Device will have the weakest processor (performance wise) but does have the advantage of being customised for it's particular display. Your 3080 vs Lumagen Vs Envy (etc) will be on par performance wise.
The question then gets down to how well the various algos used for the Scalers/Enchanters/Tone Mappers by madVR / JRVR / Lumagen / Envy compare. On this comparison I've no idea!
If you were keen on the Lumagen option for most of the processing then I'd suggest:
- JRVR (when profiles are added)
- output at native (luma) resolution passing through HDR meta data (when appropriate)
The other option is to convince Hendrik to implement what you think is missing from JRVR that the Lumagen has. Your 3080 has plenty of untapped horse power, and would save heaps of coin and simplifies that chain if it is built into JRVR. It's all just algos.
Given the current state of madVR development on the HTPC, I hesitate to recommend this option these days.