Not sure I understand what this really brings competition wise.
You can basically already do the same with the current leaderboard.
Your systems brings a few issues however. I am pretty sure some people will just voluntarily stay in a certain bracket so that they can consistently be first in this bracket. Especially if it comes with rewards.
Also, this isn't pvp, so you don't really reclaim your spot, you just do the same dungeons as last week and that's it. And if someone does some higher dungeon, he would have been on front of you in both systems.
