Probably will be same. Because you will be calculated in one league.

Means , if you advance to gold league, then you will get the gold chest.

Unless your meaning is that you are in bronze league but never advanced and keep increasing the rating to the same level of gold. In the announcement they do mention that each league will have a cap rating. So you will be only able to earn cap level RShare even you have higher rating than the cap.

But this cap rating for each league, so far we do not have this information.

And also don't miss the ECR effect. Each game played(loss will drop more than win) will reduce your ECR by avg 1%
So this results your winrate matters a lot.