The Mk7 is a great car and is always going to be in demand but it don't help that most people know you can get one brand new starting at 27k, why would anyone pay 26k for a 14 plate for a used one. It's winter nearly and a 5 or 6 month wait till March on brand new 16 plate is a better option as all the can't wait for a new one people have already more than likely already bought one, their is still going to be the odd few who can't wait but not as many. Then their is all the people who lease, their are going to be lots more on the market soon and as most know its cheaper to lease most times now, why buy a 2/3 year old one when you can even buy a new one cheaper as the Apr shoots up stupidly at VW.
I see quite a few Mk7 Rs, barely any 6 Rs in nearly 6 years, it doesn't make any difference what so ever that the MK7 is better than the MK6, its supply and demand. There wasn't much demand for the MK6 due to recession etc and i don't think you could get much discount either and expensive leasing for the few that offered it but just as importantly there wasn't much supply. But Vw seem to be pumping the mk7 R out as tho its a Golf Match model and it's not going to help residuals.
It will still do alright, better than most but it will be us who suffer the usual dealer bull when we come to sell. It is not going to be no Mk6 R
Sorry for waffling on but their are a few R owners living in cloud cookoo land when it comes to prices. 
We'll have to agree to disagree - your numbers seem to add up to 3 year old Rs being sold at a fraction more than VW finance GFVs, meaning p/x'ers will get a pittance for them (considerably less than GFV). Can't see that happening as a previous buyer of 8 new VWs, and anyone on VW finance would just hand their keys back and walk away at the end of the term. They need a hook to get you buying another VW, and that hook is being offered £1500 minimum more than your stated GFV to say you have some "equity" in the car.
You can blame the recession for the MK6's poor sales, I blame VW's 20% hike in the cost of a MK6 over it's equivalent MK5 stablemate (the GTI went from £20k to £24k overnight), helped on by the scrappage scheme - most manufacturers put their prices up to cover the losses made by the crappage scheme so we were no better off. The MK6 was really a MK5.5, with very little in the way of progress or extra equipment to justify the 20% hike - the incoming MK7 looked a veritable bargain next to the outgoing MK6.
If VWs stopped getting decent residuals then people would ditch them in droves and buy Audi or Mercedes instead. As it stands, anyone with a £15k GFV will be looking to get at least £17k p/x on their 3 year old R (which will be accordingly up for at least £21k on the used forecourt), and if they bought smart with a 12% discount, they won't lose their shirt in the process.
Doing a national search on VW's own used car website, the cheapest car there is a white 5 door manual 14 plate with just under 12k miles on for £25950, and a few similarly specced cars for a smidge over that on a 64 plate on higher than average mileage for the age.
"Most" people don't know you can get £4k off a £32k 5 door R, most of the gullible public will believe most of what that car salesperson is telling them and try to beat them down by a grand and think they've scored when they get it as they've never heard of brokers.