Honestly all my st's have broken down on me, one thing I don't admire Atari for.
If you can put together an st type computer, that just borrowed technology from pc's or 68k macs then this could work.
Now I had the good fortune to own an Apple Mac Quadra 840av, cool computer, just a shame it wasn't running GEM ya?
but the computer itself has great "upgradability" options.
Hope this is helpful to your topic, I do realise it isn't quite in the same vein.