Relative value of reducing TDP on a small loop

I currently run a 7800X3D and EVGA 3080ti XC3 in a SFF case with a single 240mm radiator. I'm due for some loop maintenance this fall and I plan to use that time to make a couple of upgrades to the loop itself, including replacing my basic Aquanaut pump block with a Modultra Lobo, swapping out the 10mm tubing for 6mm (since the loop is so small), and replacing my generic Amazon fittings with nice ones from Koolance.

The loop isn't silent (runs a fan curve of 1000-1500RPM), but it's noise profile was a huge improvement over an AIO and air cooled GPU. I was wondering whether I could push it further by replacing the 3080ti, which usually hits its max TDP of 350W while gaming at ultra settings, with a more efficient card like the 4080 or lower TDP card like the 7900XT (assuming I can get some sort of Black Friday deal).

I'm assuming the relationship between TDP and cooling performance is not 1 to 1, especially in a small loop like mine, but would there much of an impact on the loop at all if I reduced the TDP by 10-15% (\~500W to 425-450W)?