If you look at it in terms of pure performance, a mk5 GTI will always lag behind a mk7 R in most respects but that doesn't bother me. Every time I get into my mk5 I realise the dream of owning one when I was 16 has been for filled.
That, and after watching reviews online that puts a mk7 R against the new Seat Leon Cupra FR, unless you need the 4wd, the Seat is the better choice. Both have the same power, can both go like stink but the Leon has 100kg less weight to pull around.