I honestly don’t think this would be very meaningful until they can fix the bracket system. My guild is currently in bracket 21, but ought to be in about bracket 3. Since I joined a couple months ago, every GW week has been, with respect to our opponents, a joke. We score enough points on Tuesday to win the bracket by a healthy margin and just play the rest of the week for fun. 10 or 15 of us are end-game players and steamroll the daily opposition, racking up impressive looking scores against opponents who have no hope against us. We have a friendly competition within our guild to see who can get the highest scores, but we all know that it is meaningless. Moreover, because the competition is so soft, the scores that divide the top few places in our guild are very close. I think I won paragon in the last GW by 6 points, and was less than 30 points clear of 3rd place.
For context, in previous guilds, I have done plenty of GW weeks in brackets 1 through 3 and it is not the same game at all. I can score well in a top bracket, but not the way I do down here.
I think your proposed leaderboard would be flooded with players like us, who spend our GW weeks punching paper tigers.