Been driving a 1.0 115 T-Roc as a courtesy car for 2 weeks now. Apart from the bigger boot which again is not that much bigger (and for sure the MK8 will close that gap considerably), it's a small car for how big it looks from the outside. More like a raised Polo. Where this is particularly obvious is the rear seats space where there is clearly less leg-room than in a Golf, meaning bulky child seats will take a toll on the front passenger's space/comfort. I imagine things will only be worse in that aspect with the addition of 4Motion on the R variant. There's also the question of if and by how much the cheap plastics will be upgraded on the R version.
Tiguan R will be the proper R alternative imo.