If you feel it necessary to block Tor nodes in some way, I think it's better to only block non-safe methods.
Personally, I don't do it, but I understand why it's appealing. I see it as a personal decision (its your website after all) and not morally wrong as some see it.
I once talked to someone working security for a Canadian government agency. They considered it against their charter and/or illegal to block tor nodes, because it could be blocking legitimate access for Canadian citizens potentially in distress, much to the chagrin of their downstream customers (other agencies). I thought that was pretty interesting.
