Phil, I am running ML, I have a copy of OS on both drives and I used an Apple cable. My mini sees both drives and will boot off either , but I naturally use the SSD. The 2011 came with just Lion, and I upgraded to ML. Today I purchased a 1T hard drive on Ebay from a seller who had "virgin pulls" to make virgin copies of 10.8.2, because if you go to reinstall it wants to go to lion, same as my 2012 wants to go to 10.8.1. I think I know where your going to make a fusion, that would be new territory in the terminal for me. Tom
Forgot to add that the ssd is 128 and the spinner is the original 500, at one time I had 2 500's in it, but never ever came close to filling it up.