yeah, its true that XRR is alot more difficult than FZR, (thats the reason why most ppl use fzr anyways), but once u get used to it, ur gonna love it. I've only been playing LFS for 1.5 month now, and i started directly with the XRR (reminds my my Renault 5 gt turbo :P).
here's a good XRR AS National setup
its the current hotlap one from TeamInferno's site, but i believe its really steady..
tip: try not overpowering and oversteering on the corners cause this car turns around really easily.