I have mine running my original HDD in the optibay, with Crucial M500 in the HDD slot. Have a mid-2012 i5 MBP, that was giving problems with the SSD in the optibay. Swapped them around - all golden.
Data-doubler is very solidly manufactured. Included a good quality screw-set with plastic "lifters", which was a very useful touch. Can really recommend it - although, to be fair - since I haven't tried any of the cheap generics, maybe they might work as well...