MTH locos I have seen do not have sprung drivers, so even if the tires did not stay on rails, they would not drop in and cause a derailment. Of course It has been a few years since I Have handled one. I did an extensive review for a magazine on the PRR J1 2-10-4. This is the same chassis as the C&O T1. The 2 rail version I reviewed would not go around 70 inch RADIUS!
All drivers were flanged. However, they did not build like typical brass 2 rail locos. The typical locos I have are imported brass models. The have jointed side rods. The side rod is the big rod that connects all the drivers to each other. These locos have joints at each crank pin. This allows the center drivers to shift in one direction sideways while the end ones shift the other direction to help going around curves. This is like a real steamer. The drivers all move as far sideways as the frame on axle bearings allow.
The MTH engine I reviewed had solid siderods. Think of a rectangle/parallelogram. The axles had a lot of sideways play, but could not move in opposite directions. With rigid side rods, when the front axle moved to the right (for example), the side rods forced the other axles including the rear one in the opposite direction. The rods did not allow both end axles to adjust in the same direction to meet the curve. With all wheels flanged, it made a very stiff loco.
My opinion was that it would not cost that much more to joint the side rods to allow sharper curves. The engine was pretty nice other than that which meant it was limited to very wide curves. My layout has maximum 52 in radius curves. I could not run it anywhere other than on straight track.
So another complicated solution whould be fabricate new side rods.
