Some CD32 games will take advantage of Fast Ram and it might speed things up slightly.
However, take into account that most CD32 games were not designed for a system with Fast Ram available, and some will not even run (i.e. Chaos Engine, or Premiere). If you were to get an SX-1 for the cd32, you'd have to make a bootdisk that disables fastram, or unplug the sx-1. I think the promodule has a switch to disable fastram, but I'm not sure about the sx-32.
A lot of cd32 games also have harddrive installers.
btw, I don't know what kind of monster harddrives the people who write the reviews use, but I have had no power problems with my sx-1 (812meg notebook harddrive, external floppy drive, 8meg simm). After all this is hooked up, if I plug in headphones to the cd32, I get power problems. However, its fixed when you press the reset button.