Update on my experience with the new SAP US 132LB track
After some time using the track both by adding new track and doing asset replacements I have found the following:
1. The overall appearance is probably the best option for US track in TRS19 provided you use PBR textures around the track itself.
2. Building new track is no more difficult than any other Procedural track, except perhaps it is a little bit more demanding of spline positions and straight track sections around the switch itself. And apart from the need to refresh the default version from time to time in the list when laying track (It seems to default to rail only version - MSGSapper has explained it is not his doing, but a TRS19 issue) I find no other issues and the overall result makes it worthwhile. I have had no reporting of issues in Driver at all, not even with the red arrow switch lever issue mentioned earlier. I do find the rusty versions are a little less obvious than some other versions for visibility, but not a serious problem. The Ballast MSGSapper has developed if fine too, and some other PBR gravel types work with it, some don't !
3. Using asset replacement does have some issues but I think relates to the fact some procedural track types are less particular that some as any issues with the track being replaced will also show up in the replacement.
4. I tested several track types regarding Moire and cannot find much difference, some being much worse than SAP track by MSGSapper.
Congratulations to MSGSapper for delivering a superior track for those wanting prototypical US spike track.