I think Exonian hit the nail on the head when he said they've got to be hot. Trouble is, in our climate, with normal driving, even in the height of Summer, they don't get hot. For me, these should be track day tyres, not every day tyres.
In everyday situations without putting your foot down, the difference between Bridgestones and almost every other big make tyre will handle flawlessly. On my latest car, Polo GTI+, in the dry on a warm day, the Bridgestone Turanzas it came on would tramp from a standstill with 30% throttle. Switch to PS4s and you need 70% throttle to make the traction control light flicker in cooler conditions and 90% in warmer (20C) conditions.
Turn in grip is woeful. The back end broke traction exiting Testos roundabout that other cars ahead took far quicker than me. I tried to do the same thing since switching to PS4s and I can't replicate it, even driving much harder (at a quiet time!).
4WD on the R and LSDs on the GTI PP and higher GTIs mask initial tramping but they can't mask lack of turn-in grip.
If you have Bridgestones on and go for a spirited B-riad drive well within spped limits, you've a very high chance of ending up in a ditch. Putting your foot down on a die-straight bit of motorway that you're already rolling on, not so much.
Your GTI/R is much more capable on Conti/Dunlop/Michelin/Pirelli etc. than on any Bridgestone variant.