I've done the trigger jobs on my models 10, 66, and 686. I am not dead sure if your gun is the same as you did not give the model number.
As for MIM, I believe it is the hammer and trigger and possibly the cylinder stop plunger (below the cylinder). I know the rebound slide is not MIM, and I believe the "hand" is not either.
The Wolff kit should come with a reduced power hammer spring and rebound slide spring which are the prime determiners on trigger pull weight. Any roughness to the pull can be smoothed out by fine polishing, but (as you may know) the trigger and hammer are surface hardened and should not be cut on much. I would avoid doing any stoning or cutting AT ALL on the trigger and sear faces. That is the fastest way I know of to ruin a gun.
I don't know any smith to recommend, but you might want to check with SW. The last time I heard they quoted a pretty reasonable price for a trigger job.
I will say this (here come the flames) SW guns are by far the easiest of all wheels to work on. If you get a good manual (like Kuhnhausens) and the correct tools, I believe most people would be able to change a hammer and rebound slide spring (read the manual first). Brownells has all of the above. The only smoothing most SW's need is some persistent dry firing. Add the new springs (and good lube like Tetra grease to the internals) and your gun will have a very good pull. If you still want a trigger job after that, spend the money.
