We shouldn't expect too much from such a small engine. Most reasonable folks on "that" forum might be happy with say 18-20 MT 40' boxcars on a level track. Anything less will be good for at least 30 pages over there.
In the rest of the normal world, 4-5 cars would be all we can reasonably from a small industrial switcher. BUT those 4 cars should be handled smoothly at low speed. If it pulls that off, this critter will be a winner.
