I don't think there's more blur/mirror slap blur with the a higher res. back than a 22MP back.
But in my case I'm a 95% tripod studio guy.
I think the best solution is to try out the P40+ and see if it works for you.
Now for me, i think that my 60MP images look sharper than those from the P25. reasons can be:
- experience: the longer I work with these cameras, the better my focusing becomes
- tolerances: out of a batch of backs, maybe there's one who's better calibrated/works better with my body than another
- the new screen, focus mask of the IQ backs which really help me
Probably a mix of these 3 things.
Yeah, size is really a problem, we are 100 people here working at my place, the photographer (me) takes up to 85% of the server space
I was used to export 100% Tiffs all the time, now I find myself exporting 50-75% size of the original 60MP.