so, for whatever reason, your link isn't working for me.
with that in mind, the best answer i can give you (assuming your gear doesn't suck and you know what you are doing):
whatever you are comfortable with trying.
if you're in conquest badge gear and toc heroic gear and have a decent weapon you CAN tank just about anything other than hardmodes, so in the end it's whatever you feel comfortable doing. and if you don't feel it yet, then tank more heroics, and try to pug into a smaller ten man raid, until you feel confident with what you are doing and holding threat on mass dps.