I tried it this morning with my 70 warlock and lvl 9 warrior running around Mulgore. They were not grouped, and i didn't have the warrior in a group with another low toon, so i don't know if that was the case.

When i killed a lvl 8 wolf, using the method above, i got 27 exp. When i killed a different lvl 8 wolf without using the method i got 54 exp. So do i need to put the warrior in a group with another low level character on the other side of the map?