[Xaive]

Personally, I like the way it was in CoH and CoV. Grouplvl had to be within 5 for everyone to receive xp. However, you could "sidekick" someone of lower lvl (there had to be at least 3 lvls difference) and they would become your lvl -1. So your group has a lvl 5, 12, 15, 17, 18, and 20. The lvl 5 could get "sidekicked" by the 20, and the lvl 12 sidekicked by the 18. This was only in effect as long as they stayed within a certain range (50m or so). So the group is now lvl 15, 17, [17], 18, [19], and 20. The sidekicked characters only have the abilities they have learned up to that point. But their attributes have scaled as if they are the higher lvl.

CoH and CoV I think had the best/easiest grouping of any other MMO I have played. And whether they call it "mentoring" or whatever is fine, but I agree there should be a way to allow people to group with others more effectively.