I think you can get a different feel from the overall condition of the machine, and the later sprung keytops revolutionise the touch but, seen from below, I am pressed to tell any apart up to the 4, at least.
The carriage and body construction are what's most obviously different (parts that look the same from the outside are assembled completely differently), as well as the parts for shifting. But yeah, much of what's inside appears to be the same.I have two SM3s, one really really beat up and one that's quite nice, and they feel almost the same, whereas the SM2 feels like it's almost completely different. I'll have to get another SM2 at some point to compare accurately though.
That. Is amazingly beautiful machine!I have yet to get my hands on an SM2, but I'm certain it'd be a great machine. You've also photographed this one very nicely. Great score!
They definitely would look great together. :) The pictures involved a bit of wrangling with auto functions but they turned out quite well.I realise I called yours an SM2 by accident on the link, I've fixed it now!