There is something that is hard to describe, even using words like "ambiance" or "slice of life" that describes the most fragile asset that the C&TS has. This eggshell thin coating - maybe only as thick as a coat of paint, is what distinguishes the C&TS from more touristy railroads like those at D&S or Knotts, and those RRs are a step closer than anything run at Dollywood or Disneyland.
If the C&TS is to be driven by marketeers to attract riders, and this includes adding a "Thomas" to the roster, that thin veneer of authenticity will be lost, and very hard to recover.
Yes, I know the cars are not originals, but the sense of seeing a train full of them out on the line does make it seem like I am looking at 1935 or 1948 and not 2001. THIS is what should be marketed to the hilt - "you've seen the prettied up toys, now come to see how it used to really be like." Yes, it is still an illusion, but it is a different one than you can usually get at a "tourist railroad".
Trains don't have to be pretty to give a rider a great experience. Parlay the differences, not try to be another "me too".