I believe the visual quality isn’t any different purely on the upscaling, the improvement is with the additional cores in the 40 series cards doing the upscaling faster giving improved frame rates. There are a lot of variables when it comes to VR - the headset itself is a big factor. 30 series cards can give decent performance in VR as will the recent AMD cards but the general advice would be to go for the best 40 series card you can afford as brute force goes a long way to giving playable performance in MSFS VR.