Having just punished a set of F1s, I've nothing bad to say about them at all - excellent tyre.
I'm on PS2s now, only thing I've noticed so far is a slightly stiffer sidewall aiding turn in. Grip is on par.
Which versions of the F1's did you have Tony? Most, if not all, of the current Assymetric range have a choice of extra-load versions with stiffer tyres walls.
Just for the record, I'm actually running GS-D3s at the moment, not Assymetrics. Reading around, the jury is out on which of the two is actually better performance-wise, although I think I'm right is saying the Assym is meant to supercede the GS-D3. The general concensus is that the Assymetric wears better but grip levels are more or less equal. I do find it quite easy to scrub out the shoulders on the GS-D3s though, so perhaps I might opt for extra load Assymetrics in future. Assymetrics are said to be quieter too which must mean they are really quiet, as compared to the awful Conti's the car came with, the GS-D3s aren't what I'd call noisey!
F1 Assym Extra Load, which replaced the GS-D3s I bought the car on, which I personally thought were toss.
They did roughly 14k, inc 2 ring trips and a few track days. They can be properly rotated which helps too. The PS2 just seems to have a stiffer sidewall, and slightly harsher ride along with them... still not as good as my PSCups mind!
Fair-doos. GS-D3s were generally pretty highly rated, and night-and-day different to the part worn Conti's they replaced, so the Assyms and PS2's must be rather good.
Having driven a CSL on PS Cups, they are very good - they'd be a bit of handful in this weather though!
mojo, you should be ok safety-wise so long as you have the same tyres on each 'axle' although it would be preferable to have the same on each corner. Exaltos aren't bad, they're just not as high-end as PS2s. Can't comment on the pricing, perhaps Exaltos aren't as widely available in the GTi sizes. Perhaps you could srub-in the new ones on the front, move them to the back then wear out the Exaltos on the front before replacing with the same as the other set. Depends how much cash you want to blow on tyres in one go!