can't speak to your fusion drive. I have a 2014 MBP with 512 SSD. It is working fine, and has been working fine throughout the developer beta process. Seriously when I see some of these rants about all these "problems", really? comes to mind. I heard one major gripe session about external monitors (just check your color profiles on settings/displays, dah, and make sure color shift is off. - worked for me and quickly). So, not saying there aren't any legitimate problems, just none that impacted me. I seriously wish those who did encounter them would be more specific and do a bit of diagnostic work as to what is the culprit. some people run some crazy crap, that might be a big source of their problems. It seems there were a few issues on M1, but I would expect a few teething painsI’ve got a late 2017 27” iMac with 2TB Fusion drive. Is it safe to install Big Sur yet? Read some reports that it doesn’t work well with fusion drives? I’m still on Mojave and runs fine.