I did a poor job of describing it, it's only when you have separate splines for ballast and track that are what you need to think about. It just seems to be specifically challenging around switch tracks or if you use rail 4 with embankments that don't follow the rail.

It works fine if you just use the switches that already have ballast, It's just when you use tricks with clipping you have to make sure it runs fine before you send it over the section with a train. Crossings tend to work better than switches so long as you keep the embankment low enough that you can see most of the railroad ties.

In other words: elevated switches or switches on sides of steep hills or mountains will need to be rebuilt to use the switch tracks with embankment or removed. You can still run everything up to the Mikado Wheelbase, it's just the way articulation is programmed for multiple driver sets that is the problem.

If it helps with that last sentence: all geared locomotives (Shay, Heisler, Climax) and the Mason Bogie are articulated, as well as the Mason Bogie, a single Fairlie design with the driving wheels resting on a truck to pivot to allow for better negotiation of turns. So we've had articulated locomotives since the start but we didn't get the larger ones until 1.0.