One thing I can say about the GT-R is that it inspires confidence. This is something the RS is said to do as well. On the track, it is the drivers job to work the vehicle to it's maximum potential. On the street potential doesn't come into play as much as drivers ability to push beyond their comfort level and keep it there. I think the RS will have the ability to leave many mountain carvers in the dust. There are something's that can not be measured and that is one, how the vehicle helps the driver become a better one. Rhythm is key and on a track your sense of speed is lowered where on the street, the opposite happens.
My point just being the RS will make a great fun track car but won't be the ACR of hot hatches. If your ego gets shamed the RS is said to be extremely fast and almost untouchable on a mountain road. I don't condone racing on the street but I'm sure if you come across a chap in a vehicle that outguns the RS you should atleast be able to keep up with him on a canyon run, or maybe even pull away

. Goes back to the driver as always, but it is a lot harder to extract that performance on the street then it is the track and the RS is said to let the driver to be able to do that any where.