Just over a week ago, I went from a 2016 DSG GTI to a 2017 DSG R.
Did around 11000 miles on the GTI, and probably around 200 miles in the R. (Not much experience with this vehicle yet)
Firstly, I rate the GTI very very highly, I think it is an exciting car, smooth, refined, comfortable etc etc. (most people have similar opinions)
A friend bought a Clubsport around 3 months ago, this got me very interested. I then drove a couple of Clubsports, and felt a tremendous improvement on the GTI. Even though the Clubsport has DCC, I still did not like the lack of traction from a pull off, which is by far my biggest gripe I had with my GTI.
(EDIT: many forumers install mods that improve lack of FW traction, so there are options to improve on standard)
I decided to purchase a Clubsport around 2 weeks ago, as a friend loved my GTI and offered me a great price for it.
Went back to the dealership, and the sales guy, (he sold me my GTI) insisted I drive the R. I took this for a spirited drive early on a saturday morning, and at first I did not like the extra noise coming from tyres/haldex, steering felt a bit less rewarding, generally was not overly impressed.
But as I drove more, understood the differences the R offers, and stuck the DCC into Race mode, the car really livened up, started growling and showed a side that neither the GTI and to a lesser extent, the Clubsport could offer.
Added to this is the fantastic grip from a stop, the R started to feel like a very compelling package.
Plus the demonstrator that I bought has just about every extra factory option installed, my GTI only had xenons, s/r, leather, PDC & DSG.
TLDR: GTI is brilliant, adequate for most people. R is special, more for the enthusiast.
GTI offers more feel when driving, R more competent and mature.