There were 2.88MB floppies, or... I think that was actually an encoding thing? That is, I think you could take a "standard" 3.5" floppy and use special software to format it up to 2.88MB. (Maybe it just changed the track sizes or something, and hoped your disk was high enough quality to take that)

ED floppies have a different media notch. You can't get higher capacity in them using HD disks. You can however superformat HD media to 30MB in the later LS120 drives. The catch is they don't support random writes. New data requires a total rewrite.