Aren't those docks only intended to be used temporarily? I don't think you're supposed to leave the drive in there for extended periods, which lessens the need for cooling.
It is used only intermittently -- for a few hours every ten days or so when I do a full system backup. It heats up quite rapidly, in half an hour I receive notification that it is approaching the temperature limits (Acive@ Hard Disk monitor program.) The dock is parked in a corner of my computer hutch in stagnant air, even a little bit of air circulation will keep it cool.
tanstaafl.