Admittadly, I do not do a lot with passenger operations, only recently creating a "Commuter Division" of my railroad, but I have not noticed that things do not work as expected because I have the oldest version (cross compatibility between TS2010, TS12, and TANE) of the passenger assets listed in my Station and Coach asset's Queues. All three Trainz programs seem to handle using the most current version, respectively, of each passenger asset just fine, loading and unloading my trains as expected. When I look at Dependencies in each version's CM, they all show the most current version being used, even though the oldest is listed in the asset. ( I think I just said the same thing three ways, sorry, not trying to be obtuse.)