If you can negotiate a warranty to go with the 2013, then to me it is a no brainer and the $40,000 is better in your pocket than anywhere else. Even if you can't get a warranty from the dealer, for a few thousand you can purchase a good extended warranty for the items that are not still under the manufacturers warranty and still have money left over.
Naturally the mileage DOES NOT tell the full story since there could still be a lot of wear to the interior and other systems if the coach was used every day of the year that the previous owner had the coach. If the interior shows little or no wear, save the $40,000 and enjoy.