Interesting I was not aware of that. I was told the reason was that in addition to a different format, the drive was more flexible so that it could adjust more dynamically. But it seems that you could store it more efficiently and get similar results on PC.
That said, I found a forum post that claimed an Amiga could store 1MB (1.1 in the comments) on a DD disk (standard size is 880k on Amiga, 720k on PC). So perhaps an HD disk could have been formatted to store over 2MB? I wouldn't be surprised if there were some drawbacks to this method that makes data corruption more probable.
>small pockets of Amiga users that could store 1.76mb
realy reaaally tiny fraction of Amigas userbase had access to HD floppy drive only ever shipping in ONE top of the line most expensive model 4000. It was a custom modified Chinon FZ357A spinning at half rpm, needed because Amiga could only handle 250Kbit/s data rate while standard HD floppy drive uses 500Kbit/s. Commodore being hugely mismanaged didnt invest anything in engineering, they lacked will and resources to update technology in its subsequent models. 1994 A4000T, the very last Amiga ever manufactured shipped with the very same Chip responsible for sound and Double Density floppy interfacing as the very first model 1000 from 1985.
> drive was more flexible
Stock Amiga FDD was standard and could be replaced with PC after little pinout modification. Controller on the other hand could be called software defined as it lacked any smarts. It could only decode/encode raw datastream to/from ram buffer whole track at a time. In contrast PC controllers target specific sectors.
HD 3.5" disks have a 2MB unformatted capacity, so I don't think anything could go over that. The Amiga drive was certainly more flexible (and some games used weird custom formats as a form of copy protection).
I relied on it for years until CD writers became common and affordable.