Heavier as it relates to the Must shaft is sort of misleading. In Radial, yes it is .1 oz heavier than their previous shaft, but where the increased front end weight difference comes about is not really from shaft weight, but from the built in weight being moved forward about 6"-8" from it's previous version. So while the shaft weight of both versions is similar, the Must balances more to the front. none of this changes the deflection of the shaft as the weight is still 18-20" from the tip.
I think this is one of the reasons people like Revo also as they balance more to the front. Also you can custom order, or at least you used to be able to custom order a Revo shaft in weight and balance within certain parameters. So if you wanted one a few tenths heavier, or slightly more forward balanced you used to be able to order that, at a cost of course.