You'd have to be a pretty efficient quester to gain 1-1.5 levels in a <10 minutes which is what you get boosting with RAF.
Printable View
How does boosting compare with 5 at level characters running the dungeon normally?
Fastest way to level is still 4 slaves following a max level, geared out the ass booster. I've been boosting with an 83 dk and although its fast, its nowhere near as fast as what others are getting with 85's in purples. Still hell of a lot faster than questing or a 5 man group. If he had more aoe capabilities it might go faster, dps is my biggest issue atm.
Essentially boosting trumps all because of time investment.
Once you hit 15 you can be 23 in 1 hour from stockades runs.
Another hour you are 35 from SM runs
Another hour you are 45 from SM runs and a run or two of stratholme
Another hour to hour and a half you are 58 doing LBRS runs
Another hour you are 65 from ramparts and a few sethekk runs
Another hour you are 70 from sethekk + UK
Another hour you are 74 from nexus (2 runs) + DTK + 2 runs of Gundrak
Another hour you are 78 from another gundrak run + AoA + 2-3 HoL runs
Another 30 mins and you are 80
Total time: 12 hours from level 1 with BoAs
If you quest... You can see that it takes you 2 hours to do 1-15 or so. After that your travel time increases due to quest hubs being everywhere and doesn't actually get any faster till flying in outland.
You can have 15-20 mins or more of every hour be travel time between quest npcs, quests and the next zone due to raf exp requiring you to move zones very rapidly.
Druid feral/guardian is pretty fast and my favorite by far. Sprint, stampeding roar, skull bash, and wild charge get you all over an instance pretty fast and you can ranged pull with faerie fire. You have pretty much unlimited high output aoe with berzerk+swipe in cat form, when the instances get higher level (60s, 70s) you can switch to bear if needed and thrash/swipe. Since 5.0.4 you can now break roots without using your sprints, which helps in places like BRD with those damn nets.
Mage aoe output is also high and unlimited but it's harder to tank really large pulls being in cloth.
DK as frost has good aoe and ranged pull, but there are cooldowns and no way to switch to tank if necessary. Blood DK can tank anything but aoe dps is lower. There's also no way to speed up travel time in the instance due to no charge/sprint and no way to break roots.
Warrior has good mobility with charge and heroic leap and such, and tank spec can put out good aoe damage, but you can't sprint.
Paladin was my favorite before I tried druid. May still be good with mass exorcism and such but overall I don't think they have constant high damage aoe like a mage or druid.
Rogue/hunter/warlock I don't know.
Shaman suck.