I used F1 at many years ago(10 +/-).
I can say,at the time,it was one ,if not the fastest rubber around,with a good spin,but when you have much speed,normally you have inconsistency on your strokes.(you lose control).
It was ok ,since its easier to drive with it,if you use an all+/off- blade,it is awesome.
Found the sponge a bit hard(imo).
Compared to nowadays offensive rubbers,it loses some points,but still a great weapon.