I see that as more of a transitional thing. As in that check box option may not be there forever. The goal of the exercise was to have an effective reason to get permanently fixed shapes for the USx line of track loaded up into the Global folder of this forward-looking ace-less installation. It's kinda the same reason I've gone through all the 'transitional' rolling stock packs (ones that came with both ace and dds files). When uncompressed, I was a bit shocked to see the randomness of both ace an dds calls in the same shape file, as if they were leaning very heavily on a user-selectable checkbox setting that may be temporary in the end, to make these new rolling stock items work. Needless to say, I changed them over to dds as I came upon them, to make sure they still run fine after the check box potentially goes away.
Pauly, ORTS BNSF Seligman does have different track compared to MSTS Seligman for both ATSF and BNSF, but it is unknown if it is now convertable or not. My guess is probably still not, at least not without some custom US3 shape creation. But all I needed was one convertable route, like Scenic, to be the reason to get those permanently fixed track shapes into that Global folder, and to be available to other Xtracks-based OR-only routes released by them in the future. I would like to see any future X-tracks-based routes from them to be more compatible with the existing slate of USx shapes, either that, or they need to supply the missing pieces.