It doesn't matter what the intention is. If a low rating player is in a group with a high rating player, and the monster they kill is "easy" for the high rating player, the low rating player really should not be getting any XP.
That's what the system does now. I was agreeing that it needed to be a little softer for smaller differences in rating, but wanted to warn that we were not going back to the days where a low rating player could earn rapid experience by grouping with a high rating player who then slaughtered easy targets.
I'm intentionally not using any numbers yet, as that will be based upon number crunching and experimenting that we have not yet done.