If you think the hub runs cooler with a smaller fuse you are just imagining it. The only effect of using a fuse smaller than called for by the device's specs would be the fuse blowing unnecessarily. Also, a fuse doesn't protect from power spikes. It takes a good surge protector for that.
I think what he meant was, the fuse itself was getting hot. There have been reports of the plastic body of the stock 40A fuse melting and roasting things around the board.
https://bitcointalk.org/index.php?topic=336911.0Hope everything is getting better for you, SSB.