In defense of the new tracks, the trains did seem to careen around corners a bit too much.

I'll tell you what though, took me awhile to figure out why nothing was lining up properly. I have a saved blueprint that is just two lengths of straight track with a rail signal on both, set to the length of a 1 engine, 4 car train and separated by the width of a (not in the blueprint) turnaround. Yeah.....that blueprint needed a quick adjustment after laying down way too much track.

The only bad thing about the new tracks is that roundabouts don't fit a chunk

FYI: any old rail seems to have been converted to "legacy rail" which isn't the same as normal rail. I found that I couldn't place my (old) blueprints down on top of (new) rail that I'd placed manually because the tracks aren't technically the same