Good point about the dust, Michael. A couple of years back I rode that 4-day charter with 315 and 463, on which 3 of the 4 daily departures were out of Antonito. On several occasions, the rider gon (as well as the caboose platforms) became a very inhospitable place, because chasers were continually leap-frogging the train, stirring up a ton of dust as they sped by. I suspect that most of them never even gave a second thought to the effects of their wake.
If folks are going to chase, their goal needs to be to do nothing to detract from the experience of the folks who are paying the lion's share of the "freight." If those folks decide the experience isn't worth what they paid, everybody loses.
I just signed up for a charter next year in another state, in which the railroad pledged to have their railroad police accompany the charter to physically prevent chasers from interfering. If everyone shows a modicum of courtesy to everyone else, it should never have to come to that on the narrow gauge.
/Kevin