What strikes you as the main difference between the two, now that you have one?
The biggest thing is the cylinder turns the wrong way on the Smith...LOL.
IMO, it is not fair to compare the Model 15 to a Python. I'll sheepishly admit the Smith is pretty darn smooth, but it is not near as smooth as my roughest Python.
The best comparison for a Model 15 would be a Diamondback snub. However, I don't have one. Of course as far as $$ goes, you could buy nearly 2 Model 15 snubs for every 1 Diamondback. With that said, I'll be the first to admit while I like the Diamondback, it certainly isn't "twice" the gun the Model 15 is. However, I'll hazard a guess that the Diamond back would have a slight edge when it comes to trigger smoothness...not by much, though.
What I do have to compare the Smith to is a MK III Lawman 2". They are of about the same vintage, about the same size/weight. and can be had for about the same amount of $$ today. I'll give it to the Smith when it comes to double action trigger pull. It is smoother. Of course in all fairness, the Smith is used and I would guess has seen more rounds than the Lawman, which has only had 18 rounds put thru it, which I put thru it the day I bought it. Switching from one to the other takes a couple of dry fires to get used to. The Lawman's hammer travels back farther before breaking. Of course the key advantage to the Lawman is the fact it is a .357.
Ruger,
I believe you are correct that the 2" nickel Model 15 is a rare bird. It is the only one that I have ever seen. I knew just enough about Smiths to be armed with that knowledge.