I have a 9900K @ 4.7Ghz locked all cores and 2080Ti (OC +150Mhz core, +500Mhz RAM) 
OXR 65% runtime preview enabled, repro on always and in MSFS render scaling on 70% buildings and terrain on 100% rest on medium/enabled, all traffic / ai off.
Yes the reprojection has artifacts and yes clarity isn’t perfect but it’s 45fps (therefore a solid 90fps in the headset) pretty much everywhere in any weather. Even if I change OXR to 70% I notice it as I’m super sensitive to stutter so this is perfect for me, it really does feel like the cliff house so that absolutely is possible and the headset doesn’t jump around at all - the tracking is very smooth and accurate.
With a 3090 I would have thought you could have had my settings, keep OXR at 65% and as @AIRBORNE4795 has said put the MSFS TAA render scaling to 100% that should be perfect, plus a few graphical settings on high as well like textures and clouds.
I think the point is it’s a balance even on a 3090 but if you are careful not to stretch things too much you can have a blinding experience in VR and for me this is a joy to put on the headset.