It is my preferred method of levelling, however you get the odd dry spell which really grinds on you. If you exhaust the quests and have to repeat the instances because nothing else is available it can feel slow.

I would do it on every team if Blizzard would remove the role requirements....

I can't vouch for 11 hours, but it is generally fast. It does feel like self boosting, just playing at the correct levels.