Seen a few non R Golfs with this fitted but still not seen any conclusive evidence that the sub frame makes a Big difference to a road car.
I am guessing that it was the Mount kit that made the big difference to the way the car feels.
Comment from You Tube
I've got the S3 aluminium subframe with the RacingLine dog bone mount fitted to my MK7 Golf R for 2+ years now. It's definitely lighter, but didn't notice a difference in steering response.
Whilst the R will be 4wd I have seen FWD Golfs with it fitted but they all talk about weight for the track.
Hopefully @Aellis will reply with info instead of Youtube only.