Cool machine, funny I was looking at a 241 sitting outside a place here in town just this morning. They have a sort of semi permanent garage sale there. Guy wants $400 for it. Way too rich for my blood plus it was missing the cover plate on the needle end. Your 31 looks like a very good basic machine to me but I really know nothing about the commercial models.
Nice Avatar. What kind of armor? It may be off topic but I'd like to see more.
Rodney