I guess it just boils down to quality control. I don't doubt their prototypes being that light, however, when you mass produce things, and especially, when you want to make a good profit, you can't be discarding elements that are a few grams heavier than spec, say. Add those few grams here, few there, and you arrive at a quarter pound heavier final product. Maybe, also, they found some issues in the prototypes between the initial hype and the production, so they beefied up some elements.
As to what's great about the R7 over the older models? It is stiffer and better damped.
_MK
As to what's great about the R7 over the older models? It is stiffer and better damped.
_MK