Just a thought....
I have no idea about hardware, so I might be on a very wrong path here.
Most of us use our atari with harddrives 60-1000 mb. Very few of us really need 40 gb, especially on an ST.
Wouldn't it be possible, to connect an adapter throu - say cartridge (as discussed here) that is an adapter for compact flash memory cartridges or secure digital.
This will apear as a harddrive on the ST - say for instance C:.
They are fast, small and very compatitive in price.