I recently bought a 637 (same finish as a 642) and a 60 (all stainless steel).

The 60 will outlast me, but weighs 50% more than the 637, so I carry the 637 more often.

I bought the 637 because I was told the finish would last better than the 437. I see from this thread the 437 would hold up better. I have some Renaissance Wax for my old Colts, and will apply some now. If the finish starts to show wear on my 637, I just won't worry too much, I'll keep putting it in my pocket.