Considering that I only have DRK left to level as far as tanks goes and that it feels like utter crap at anything before 60, doing level 50/60 roulette is akin to playing Russian Roulette with 5/6 chambers filled. The chances of getting a level 50 Dungeon are much more likely since there is just so many of them to begin with and some are required for story progression (Keeper of the Lake, Snowcloak, etc) that I just generally try and avoid it on my DRK.
That and because I utterly despise tanking in general but that's another story.