I own a standard 686, but I've shot the SSR before.
IMO, the SSR's a fine gun, and if I wanted something (slightly) more tuned than a standard 686, but didn't want the hassle of sending a standard 686 out to a gunsmith, I'd opt for the SSR.
IMO, the interchangeable front sight is the single biggest upgrade, and it alone likely costs the price difference to have a standard 686 upgraded to interchangeable sights. The first upgrade I'd make, though, is to replace the factory red ramp with either a fiber optic, Patridge or gold bead.
Aside from that, I don't recall the one I shot being any more accurate or having a much better trigger than a standard 686, and S&Ws chamfering is very conservative (you have to look hard to see it). The partial lug lightens the entire gun a bit, but the lighter muzzle also jumps a bit more under recoil.
All said, though, the best gun in the world is the one you enjoy shooting the most, so it sounds like you may have found a gem! Good luck - we'll expect pics & a range report soon !