This has been talked about alot on here-
Yes, they are good on rails. Just keep them waxed to keep the base good. If you get them new, wax them and let the wax dry, wax again(same wax as before, no scraping) and let dry, scrape it off and repeat. Wax them every few days durring the season. I just skied mine for the first time two days ago and that whole fast thing isn't just a sales pitch, these are faster than my GS race skis.