Well I have just gone the other way, from a Mk6 Gti to a Mk5 Ed30.
I had the Mk6 for 3 years and 45k miles as a company car and absolutely loved it. Had to have a new water pump but it was very reliable and economical. I enjoyed the long drives and the motorway cruising.
For about a month I had both cars on the drive so was able to make comparison.
Performance wise the Mk6 feels just as fast as Ed30 in normal driving. Ed30 has bigger lungs and in mid range would leave it behind. Not a lot in it though but now my Ed30 is 300bhp its in a different league.
Mk6 is quieter, smoother, more refined, more comfortable, more economical and makes a lovely noise. It is more grown up than the Mk5. A journalist wrote ' its the GTi that your Dad would drive' which sums it up perfectly.
But Mk5 handles better, feels more alert, steering feels quicker and is just more fun. Thats why I took a 'step back'. Every journey it says ' take me on and spank me !'
If the MK7 can provide the qualities of both cars then we are in for a treat.