Yes, but even the main race in escc is quite short actually (about 1 hour), only one pitstop is needed. There's sprint race also, where fzr really shines. So overally fzr is better for the whole race night. (Did I forgot to mention qualifying, where fzr is better?)
I like xrr more, but then noticed I wouldn't have a chance agains fzrs in those quite shortish races. I decided to pick fzr, and it's much much harder to drive, especially when rear tires are at their hottest state, after couple of laps. They will settle down when they wear though.
But when races are about 2h long like in endurance league, they're quite balanced (don't know about the fxr, didn't see one in my div). I was able to finish with only 3 pitstops in my xrr, when some fzr guys had to do 5. The track was Westhill.