bj wrote: How thoroughly has it been tested?
I tested it intensively with lot of diverse format floppies.
Read page 'The Floppy Mystery" , where are explained problems,
incompabilities with floppy formats.
Of course, you are welcome to be tester, to contribute.
To be sure that floppy is not protected: watch is some error appears by making image (CRC, RNF). If not, it is most likely unprotected. If it will run then with emulator, 100% . Here not count games on original disks - however, those with 'manual' protection usually are unprotected from copiing, except few cases.
I'm sure that floimg is in this stage, version 0.7 tested more than any other imaging program for Atari ST.