Questing will be much slower than boosting. I've boosted 4 teams to 80 in the last 5 weeks and once you have a good routine of where to be at what lvls it's extremely quick.

I've started leveling the teams I've boosted in Cata and with the CRZ's it's a nightmare. The number of people fighting for mobs and ground spawns slows questing down to a crawl. I couldn't imagine trying to do it from 1 to 80.