Did you read the study that Google did on the reliability of HDDs and temperature? It's funny but they reported the lowest failure rate with drives operating in 40s. Google it. If anyone should have a decent sample size of HDDs it would be Google. Unexpected result, but now I put my Home Server in a cupboard and the drives are at 41-43C and I'm not losing a wink of sleep over it.
Well I would add two things.
1. Those temps are when the drives were idle; it will be a different story when they are under a load.
2. The main reason for swapping cases was the fact that I need two hot-swap bays in the case which I can access through the 5.25 bays. I was only able to find one type that would fit in the FT02 but the drives reached 56c in them which is likely because they have no fan (the drives tested in the screenshots were not in hotswap bays but were instead drives in the plastic cadge in the FT02 and behind the 120mm fans in the PC-P50). Going with the PC-P50 has allowed me a much wider range of choices when it comes to hot-swap bays and the one I am currently using likely keeps the drives a lot cooler. I will post some results later this week when my sas cable arrives so that I can connect it to my LSI card.