Soul Level Range or New Game Range?

Demon's Souls and Dark Souls both use a soul level range for co-op and invasions.

I think it would make sense if the range wasn't based on your soul level, but on which round you are playing. Whether you were soul level 1 or soul level 712, if you're fighting the boss in NG or NG+++, the enemies and the boss would have a similar level of difficulty.

If the range was based on the round, the player interaction would be much higher and if you wanted to engage in player vs. player fighting, you could pick a round (like NG5).

I know I'm "blue skying" here, but what do you think?

It would be interesting, it might cut down on certain forms of griefing, but could at new ones such as getting to max level, but not going into NG+ and being way way stronger than any player could possibly be. As well helping out people in NG+/++/+++ would become a real pain if your SL didn't matter.