i have bad experience with this...
my mediator required me to use a AT psu ;( and since my amiga is powreed by ATX meant that i had to use 2 psu's ,
it resulted in that the fans on the weaker psu died, and almost killed my hdd's + keyboard adaptor (the AtX OnE) ,
on the ATX i had keyboard connector , 3 hdd's and cd + cdrw
on the AT i had mediator + the diskdrive etc...
but i forgot to mix the 2 grounds, so as i said....wasnt a good pleasure, but it seems to be OK now (when i am back on 1 psu)
i didnt fry more than 2 psu's (ATX ones) , 1 went first and i belived it was old and bad so i just got another one....and same happened again (after a 2+ month period)
hope this helps out, anyway i invested in a 400watt one...to supply all, and ofcourse its an AT one since my mediator is AT ...AAAAAAAAAAAAARGH...
(had to replace my rbm towerhawk adapter also with an elbox one... (keyboard ad.)
good luck