Speaking from my experience on my shadow, tanking with a shadow/assassin is a little bit more of a gamble than the others. There have been times where I've practically solo tanked bosses in flashpoints, and then there are times where I've been smashed by an overly large group of standard mobs (in both instances the healer had bugged/died). The glory moments come a lot more often than the /facepalm moments, but it is something I've run into that you might consider.

Bumping because I think it's important.