Make Iridescent play Iridescent

Ashendale

What would happen if when a certain number of players reached Iridescent grade during the monthly cycle, it locked Iridescent-grades into only playing against other Iridescent-grade players?

I suspect match times would increase a bit for them, but how do you think balance and perceived "fairness" would feel? How do you think it would impact the feel of the climb for non-Iridescent players?