So I hit 45 and thought I'd try out the instant adventures. Before I knew it I was a couple of hours in and already level 48, had tons of notoriety with Mathos, and had 20k planarite plus about 70 of the things to open up for essences or other goodies. I didn't even think to use one of my experience potions or I'd probably have hit 50 without even trying.
I had no idea it was so efficient not to mention it's pretty fun blasting through areas with a big group of people.