After reaching 50 over the weekend, I just don't see how it's possible to go from 40-50 without boosting. My number was just under 8 hours from 40-50 using this RAF guide with my current tri-boxing team. I'm currently doing the Hinterlands set of quests and should be dinging 53 after I turn-in the 14 quests for what I figure to be over 325k worth of experience. By the way, I'm lagging just a bit behind the intended levels because I skipped most of the chicken quests...just didn't want to be bothered with grinding mobs looking for the drop.