Are hardware profiles only for disabling or enabling devices? Can you have one driver loaded for a device in one profile, and a different driver loaded for the same device in another profile? For troubleshooting purposes, I'd like to be able to switch between generic MS drivers for my SATA drives and the motherboard chipset drivers that I haven't installed yet.

I know from a previous install that I can't get rid of the nForce 4 SATA drivers once they're in without an INACCESSIBLE BOOT DEVICE error. It would be nice if I could switch between the two. I know from trying to remove the SATA drivers that using the "last known configuration" actually restored them (when I removed them) and allowed the system to boot. Anything I've read online is conflicting. Unfortunately I can't try this without possibly being stuck with these drivers.

No, you cannot have different drivers for different profiles. You can load and unload different devices per hardware profile, but you can only have one driver installed for any device at any one time.