I don't know anything about the Mac platform but moving a route from TRS19 to Trainz Plus is simple. Export the route from TRS19 as a .cdp file and import it into Trainz Plus. After importing you may/will need to download and install any TRS19 assets that are not in your Trainz Plus install. In my case that was easy as I do not use any third party assets so the "missing dependencies" were all found on the DLS.
I am in the process of "upversioning" an old route of mine that started in Trainz 2004 to Trainz Plus on a PC. It had already been through several "upversions" - TRS2004 to TRS2006 (in which it now appears on Trainz Android) to TRS12. From TRS12 it was converted to T:ANE as an intermediate step to eventually appearing on the DLS as a TRS19 route - going directly from TRS12 to TRS19 was problematic.
TRS19 provided new features that the original lacked, specifically procedural track and effect layers, which I added in the TRS19 version. I have since (in the Trainz Plus version) converted all ground textures to PBR and will be taking a look at the new water effect layers. The route is far to big to be converted to HD Terrain.
I am also taking advantage of the new features and abilities found in Surveyor 2.0 to significantly enlarge the route (adding another 81km of track) and fix up the faulty terrain along another 130km stretch (the original TRS2004 route predated Google Earth). The Surveyor 2.0 tools are so much faster and easier to use than the equivalent, where they exist, Classic tools - it just took time and practice to learn the new ropes.
My experiences.
