I've had just about every mainstream 'performance' tyre on the ED30 in the last 50K miles including the GY F1 Assy and the PS3 and whilst imo there are subtle differences between the 2 (F1 having marginally better straightline grip and a comfier ride, the PS3 giving better turn in feel and better in the wet) the differences are so small from a performance point of view imo that most 'regular' drivers would struggle to split the 2..
I prefer the PS3 as they wear MUCH better and the stiffer sidewall gives a better turn in feel and doesnt suffer from the sidewall 'eggs' that the F1s did, the F1 wins on price and initial pull away grip, i'd be happy to run either on the car again
As for your experience with the PS3s, have you had any other tyres on the car in your ownership? The GTi is set up 'safely' like all modern FWD cars with a tendency to understeer when approaching the limit, stops joe public backing them through hedges
FWIW this year alone my PS3s have done umpteen laps of the TT mountain course, 5 1/4 mile runs, 2 track days at Oulton and 1 at Cadwell, 8 laps of the 'Ring and the same on the F1 track and have been spot on