The IDE-part will surely work, so will SIDE to load files from FAT-area.
The -F OS will not, since you need 64k ram.
MyIDE-2 does work on a 800, when you do the phi-2 modification to the cartridge port.
But same issues, you still need 64k for the RAM-OS to run.
At the other hand, the MyIDE-ONLY should work.
(Haven't tried this yet)
Grtz,
Sijmen
-edit-
Wait, I did test MyIDE-2 on the 800 with MyIDE-only.
viewtopic.php?p=10740#p10740