I wouldn't get new vinyl, I would get a new cover. let the vinyl sit in the sun til it goes back to normal, scrub it with a good clean, soft scrub brush and Vinyl Sauce (brand) then put the vinyl condition sauce or 303 Protectant.
N8,
As far as the discoloration of the vinyl it is the dark mooring covers that do it and it only does it in some states. It has nothing to do with a lack of quality vinyl. We have been a boat dealer for 30+ years and have have been a Centurion dealer since 1985 and we were a Nautique dealer from 1988 to 2011. We have been a dealer and/or service center for Mastercraft, Supra and Malibu over the Years and have has the same problem with ALL the brands. We have even had the plastic on the seats on a few Nautiques warp. If you get a gray cover you will be fine.
As for Centurion not honoring their warranty -- we have never had a problem with them in all the years we have carried them. Sometimes the dealer you buy from is just as important as the boat you buy.