THanks, the hot wiring diagram may be helpful. I considered the duplicator case, but primarily I would like to use the ATX case PSU's, as they are highly superior (for the money) for quietness.
Also, I already own 2 extra ATX PSU's and 3 extra cases. It would be nice if I could simply mod an existing case/PSU to suit the needs of an external drive enclosure.
The daisy chain is actually a very good find. I could potentially daisy chain from one case to another, causing the drive enclosure to turn on and off whenever I turn off the computer (in theory.) - so that's worth looking into. However, I fear that this would cause both power supplies to try and power the motherboard. Also, I wonder if maybe running sata power to the next case, with an external connect/release point might be a good, cost-effective choice.
THose AT-style PSU's are noisy and have small fans. I try to only use slowish fans 120mm and up, as I am a freak for silent operation. I was hoping there was an easy way to hook the ATX PSU up to the case power button. Somebody should design a little motherboard that serves that purpose, but doesnt have any processors or even a northbridge.