So I went ahead and did it: After a decade of using openSUSE as my only Linux distribution ever, I switched to Manjaro on my main system last night. There were a few bumps in porting my home directory and all data between distros but it worked out in the end.
At the moment I’m only running into one notable bug: The bootloader works but no theme is installed. When booting there’s a black screen for several seconds… if pressing esc during this time I see the grub menu, but only in console format without any graphics. The splash screen does appear after this. Obviously the grub-theme-manjaro package is installed so the theme should be getting installed.