Imagine an Amiga with a 10,000 or 15,000 rpm drive.
BTW - What problems am I'm going to have to deal with in terms of drive (or partition) size limitations?
You're still going to be limited by the xfer speed of your controller.
The usual - depends on the capability of your controller and whether you're using 3.1 vs 3.9, FFS/SFS/PFS, etc.