I have one of those. It would always shut down and then I had to turn off/on to get it to work again. Pain.
Current build was right when HDD prices increased. I opened the SimpleDrive and took that 1 tb out and used it as my main drive. No problems. Internal drive. Isn't a bad drive at all once you take it out of there. Bought WDB as main and use Hitachi as second 1tb. But I have kept the case for when HDD prices go down, will have external housing (but USB 2).
So anyway. I took the drive OUT and used it fine, so one would expect that, yes, you could put any appropriate drive IN.