MPG varies depending on camp location. The further you go in the better the exp. As with the mobs at Blind Hunter/Task camp and toward the zone out, mobs are on average level 69 and below. Most are blue to 70 except the named. Moving on to Odi or Enchanter, tactics, realm those are all level 70. With a good tank 10K plus hp, further on is recommended. Having a high DPS group makes this place a breeding ground for AA. With a Pal tank, Cleric heal, Bst slow/buffs, a rogue, ranger and any other high dps class for last slot, we would do an AA every 30 to 45 min. Sometime longer depending on who needs a break. After a while and being at all the camps, you will be able to colect some real nice armor upgrades. Such as any of the Mazerunner gear (mask, ring).
I found that you need a 12k + tank for RS. Mobs beyond the stairs are level 71+. I like here because mobs are fire types and our cold nukes land quite often. I was finding AA exp was around 6% per kill dending where you were, but Its almost impossible to get a pick-up group here. You need to bring a group or know from good friends to get a slot.
Whereas MPG, It's very easy to get a group. Sort of like how BOT used to be.