Ive run both the 571/572 and Ride R1 combos on my 104WGP here on outdoor asphalt. What I can say, is that they handle very very differently.
Whilst with the 571/572 combo, I generally had to go harder on the front to take away steering, with the R1's, you need to go soft soft soft to gain some back. (this is 17.5 blinky btw). The R1 front compound is pretty hard, so doesn't really generate a lot of steering. Having said that, they do last a long time (at least 20+ 8min runs), but there is a performace peak. Take about 5runs to break in, then they are good for fast times for about 7-8 runs, then start to tail off again, at least thats my findings (based on practise for the nationals demo class out here, which we all used R1's as spec tyre).
Having said all that... I've still set my fastest times with the R1's over the 571/572... so worth trying out if you can get the car setup for them.
HiH
Ed