I've found that some DD diskdrives in Amigas (found in 2 of my A1200) actually checks for the HD holes even if they only read DD disks and precent an error when using Hd disks that haven't been taped.
As said HD disks that are forced to work as DD disks are not as reliable but they do work for quite some time... It doesn't bother me much as the ADF's I write to disks are often installed onto HD stright away.
