Here is a link to a RC cold water or temperate water thread. I believe that Steve Weast (Oregonreef) also has information on his site about his beautiful cold water reef.
http://www.reefcentral.com/forums/sh...hreadid=890751
I recall reading it a while ago and basically as Steve has said - thick glass and large chiller costs are the basic drawbacks as well as the cost and difficultly of acquiring livestock unless you can collect it yourself.