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I believe you want your application to be the best it possibly can. You really only get one shot at a complete app review. Those who keep sending in letters and updates to boost the application are behind the eight ball. Some schools use a formula for review so higher numbers are definitely better.
 
If it helps at all, the year I applied early and then sent updates with an improved gpa I was told that adcom didn’t really have time to do another full review of my app. So I’d vote wait