Hi Alpha,
I have said it before and will say it again,

First and foremost the 586 was built a lot better than the 686
Second, the trigger on the 586 is a lot smoother than the 686
The carbon steel on the 586 was more durable than the 686 stainless in abrasion areas like the hand & ratchet teeth, among other things. Workmanship was better on the 586's than on current 686 variants, and they had no mim parts and no locks just to say a few things.

Eric