I'm not aware of any issues resizing a Flex Vol that is deduped and compressed. This assumes the following:
- The Flex Vol is not a Snapmirror or SnapVault Source or destination
- You are not sizing the volume so small it cannot fit any snapshots you have
If you have snapshots, you have to make extra sure you leave enough space to satisfy your snapshot_reserve, fractional_reserve, and lun reservation settings. Even if hte vol is involved in a Snapmirror or SnapVault relationship, you can still resize it, but you have to take care and resize all of it's partner volumes equally.
Hope that helps!