I've got a 4 inch blackened stainless 686-3. I bought it used a few months back. The gun was not really well cared for.
The finish has held up quite well IMO. There are some scratches and a little holster wear, but it cleaned up quite well.
I find it to be much more durable than the black finish on my pre lock PC 586-5 L-comp. That black finish wore quickly and badly. Regards 18DAI