GeneralChang,
Like RWK said, avoid lots of really hot loads, clean a lub once in a while, and it will outlive a few generations Changs.
I've got a 625-3, two 625-6es, and a 625-7. I've only had the 625-7 for a little over 4 months, and it's already got 5000 rounds through it. No wear at all. Just a smoother trigger.
I think an "N" frame would really have to be abused to wear out.
Good Luck...
Joe