Sunset 3rdRail basically does scale models as opposed to toy trains. They do convert some stuff to 3 rail but they start with a 2 rail version. That is why the stuff usually wants wider curves and less sharp switches. Many other manufactureres start with a 3 rail loco, and just put 2-rail wheels and wiring on it. Most of these have compromises, some severe, relative to following scale dimensions. One of the most common on steamers is extending the pilot deck and pilot out farther to allow the lead to be mounted forward for the cyclinders for clearance on 3 rail curves. On some this is not too bad, but for me, the ones with 4 wheel lead trucks that are done this way are just way out of proportion and do not look like the photos of the real engines.
Sunset stuff is good quality in my opinion. The mechanisms are very well done and work well. The detail is also quite well done and follows prototype quite well. Yes it is fragile, again, it is a scale model, not a toy train. by definition getting the scale or close to scale detail dictates it will be more fragile than diecast with lots of things cast on.
