As evidenced in the photos, when you have a nice spindly Rivarossi Genoa or Reno sitting in front of you, most of the period steamer offerings from MTH and Lionel look disappointing even at 3 feet (to me anyway), especially the solid look of the boiler and firebox areas.
I scan for the Rivarossi stuff on the Bay once in a while, and the Genoa seems to come up more than the Reno.
A re-motor and a Marx shoe underneath? I dunno. The wheel flanges on 3-rail switches would be a challenge, and a lot of playing with weight would be in order. Just my lowly $0.02