I think that this could be a good model for 3rd Rail. I do think that more information is needed including a ballpark price. The price may be partially determined by the number of reservations. This could be a chicken or the egg thing.
Another factor may be that it costs almost as much to design, build and import a small engine as a large engine. Buyers may be willing to pay $1,000 plus for a large engine but not a small one. This could be the reason for the lack of interest in this engine.
Small steam engines were used on many railroads to switch industrial tracks and other areas with sharp curves. Hopefully, this engine in 3 rail will at least get around an O-72 curve and possibly a tighter curve - O-54?
I would think that 36" radius may possible in 2-rail. This switcher was the equivalent of a small diesel. Small diesels replaced these switchers on the real railroads. What is the minimum radius a small diesel is expected to get around on most 2 rail O gauge layouts?
Joe