I game at 3440x1440 ultrawide, and upgraded from a 3090 to 4090. 4090 is significantly faster and smoother. And DLSS3 frame interpolation is no joke- in Hogwarts Legacy with every setting cranked up and max ray tracing, turning on DLSS3 jumped me from around 80fps with noticeable 1% low stutters and now pegs it at the 144fps limiter I set in game. Smooth as butter.
Also I mess around with some AI things like stable diffusion, and it’s much faster for that as well. As much as I hate the term “future proof”, the 4090 is more worth it in that regards, IMO.
MakeMKV (at least in windows) lets you rip a remuxed mkv without having to rip everything. So you can just select the titles, audio, and subtitle tracks you want without ripping all the other stuff. You don’t need to make a full backup and then pull all that out.