I know that back in the day when 5.25" floppies moved from 360 KB to 1.2 MB, there were lots of problems with low-density disks in high-density drives, but I have never had such issues with 3.5" disks. (During the transition from 360 KB to 1.2 MB, it was fairly common to see computers with one of each type of drive, for better compatibility. My old IBM AT is that way.)