Just looked at some figures, I think it explains why the R's are cheaper on finance.
A GTI with PP costs £27,120 and VW GFV after 3 years is £12,894.
An R costs £29,900 and VW GFV is £15,201 after 3 years.
So it costs £2780 more brand new, but it holds £2307 over the GTi GFV. So on finance you're only paying about £400 more.
Also, there are 3 year old GTI's for sale from £15,000, whereas the cheapest R is £22,000.
I'm not trying to argue that the R is a better car than the GTi, that is like comparing orange juice to apple juice, both are outstanding cars, both have pro's and cons compared to the other.