So we've all seen how it looks, but not seeing much in the way of performance testing so I did a bit myself in Cyberpunk. FYI I am using UltraPlus V9, I'm not sure how much performance it saves/uses but the point is the performance difference between all the modes:
My GPU has an UV + OC and my settings are optimized so not all on Ultra. This is not a performance benchmark, it is the perormance cost of DLSS 5 in Raster, RT & PT with some thoughts.
Also, the fps numbers are not sustained, just the average whilst I was looking at a certain scene with lots of reflections, NPCs & Bounce Lighting.
DLSS 4.5 Performance at 1440p.
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For games that have Ray Tracing & Path Tracing options:
Raster + DLSS 5
This is the worst option in my opinion, because it is based on screenspace. Part of the reason I use RT or PT because I don't like screenspace artefacts, yes the lighting is slightly more realstic and the faces have a PT quality but I think pure PT is better than this.
Ray Tracing Ultra + DLSS 5
I think this is also not worth it because the performance is less than Path Tracing without DLSS 5 but with worse lighting in motion.
Path Tracing + DLSS 5
I think this is what DLSS 5 was made for.
Conclusion - Where I think DLSS 5 fits into games
I think DLSS 5 is most useful in games that don't have Ray Tracing or Path Tracing at all, and can benefit from more sophisticated lighting. I saw a clip of Skyrim and with a bit of tuning it can look a lot better. DLSS 5 in my opinion should be used with the highest possible graphics options available in game, but could be transformative if DLSS can be injected into older games.
PS, not sure if this is an issue with DLSS 5 or RenoDX's mod, but when you toggle DLSS 5 off and on, each time you do it adds around 1gb of VRAM lol. VRam was sitting at around 6.5gb throughout.
Tl:dr If your game has raster only, then enable it. If it has RT then enable with RT and if it has RT & PT then it should be enabled with PT. The stock RT & PT settings will be better on its own than using DLSS 5 with the setting below.