TBH, since I put the winter tyres on all round, I've only noticed better grip at lower temps ~<4*C
But anything approaching 10*C the summers were a lot better.
So I decided to swap the fronts (kept the rears in winter mode) to summers, Eagle F1 AS2's.. a simple swap as I have 8 Monza alloys.
The temp outside here today was 9*C... the result? The car felt MUCH better, a lot less wheelspin and more grip in the corners.
It's set to be about 5*C tomorrow with rain, so it will be a true test. My winter boots aren't cr@p either; 'Good year Ultragrip' in the same size as the summers.
Reason for the change was primarily because I was chewing through the winter tyres at an alarmaing rate, and didn't want to get caught out when the proper weather arrives (which seems to be around Feb/March over the last few years)