Greg,
My son did it several years ago. He'd just flown in to NM the day before and had only been at altitude for about 12 hours. He left Chama sometime after the train departed and arrived at Cumbres at the same time as the train. The western slope of the pass is a fairly moderate grade on Hwy 17, though it steepens from below Windy Point to the summit.
He described the descent as not very technical but fun. Many ski areas offer chairlift rides for novice mountain bikers who then enjoy a leisurely descent...no work, no sweat. Perhaps there's a road bike equivalent possibility for the C&TS, but that would be down the road (pun was accidental). Just selling fares and running trains this season will warrant high fives all around.
If there's ever a time for all of us on this discussion board to ride the train and bring a crowd with us, this is it. The best thing politically for the RR would be high demand.
Brian