CFFA2000 in IIgs slot 7 to boot the IIgs off IDE harddisk images?
Coming very soon. (I believe this is the first time any IIgs emulator has allowed arbitrary card emulation - KEGS and XGS certainly don't do it).

ETA: available as of SVN #14868. I ran with a Memory Expansion Card in slot 4 and a CFFA2000 booting System 6.0.1 off an IDE harddisk in slot 7 and copied files back and forth between the IDE device and the RAMdisk with no trouble, so I believe the support is stable.