I have "DECIDED" on the 686 SS BUT which one??

[halfmoonclip]

Let me reiterate RX-178's remarks about 6 vs 7. A great deal of the double action feel in Smith revos is based on the fitting and geometry of the hand and ratchet; advancing the cylinder by 1/7 vs 1/6 will make a difference. I'd try to feel both before buying. This really only matters for double action.
Previously owned both a 4" and a 6", alas long gone. The 4" felt infinitely better for balance; the lugged 6" was muzzle heavy. If you're actually going to carry it, as contrasted to hunt with it, the 4" is the only way to go.
For accuracy, from a machine rest, no difference. Real world, more sight radius wins, and of course there is more horsepower in the longer tube.
Moon

 

[krand]

I have (3) 686's, all 7 shot. I have a 4", a 5" and a 6". I shoot them often. I favor the 6" cause of the balance, the increased velocity and recoil management. I shoot it much better than the 4" and the 5". It is a Model 686-4 with a pinned hammer and the action is considerably smoother than the later versions. It has a case hardened hammer and trigger, is pre-lock and pre MIM parts. My opinion is that the pinned hammer gives more reliable primer ignition with a lightened action that a frame-mounted firing pin. The trigger in the 6" 686 is thinner than the later models, which is much more comfortable for double action shooting. I have looked hard for a similar model in a 4" version for carry, and it seems very difficult to find.