Right i know its not a 3.5" HD but my Compact flash HD is setup on a real Amiga taken out put in a 7 in 1 card reader on a Windows PC with this UAE picks it up as a Amiga HD lets me copy,delete format the CF card. I even copyed my UAE setup over to a CF card once and after deleting some piccaso libs it booted fine on real amiga and in fact still is working fine.
Note once the CF card is formatted on the Amiga the PC (Windows) will not locate the CF card correctly ,i assume its the same for 3.5" HD. :-)