I would caution that we are not necessarily “home free” if a unit’s wheels successfully hold the rails on a curve tighter than the mfr. spec. Remember that in doing so, the trucks have to swivel to the max. I have seen the inside of nearly all the units I own, and all too often, the leads between the motors and their other connection points are a bit too short to allow extra swivel without tension. I have also seen the wires from the pickup rollers cut into and shorted by the sharp edge of the unit’s floor. Do the overseas assemblers really save that much money by not asking “what if” and including a bit more slack?
I wonder as well with steamers where an umbilical with four or more wires has to bend more over the life of the locomotive. And what about alignment with the infrared engine/tender couplings? Having written all this, I confess to running a couple favorite locomotives on under spec curves in the hope of “getting away with it.” 
