While I do not own a 686 Competitor, I do have two revolvers of similar design that are built on the N-frame.
My 625 Hunter
My 627 Heavy Hunter
Neither of my revolvers shipped with the very fine LPA sight.
I do have one of the LPA fiber optic sight sets on my 627 Pinto and I am very pleased with the sight picture they offer. Since the LPA sights use the Factory drilled and tapped scope mount screw holes, they are an easy upgrade to ANY Smith & Wesson revolver built on a D&T frame
On both of my revolvers I have replaced the Factory supplied grips.
Both firearms are exceptionally accurate. Both of my revolvers came from the Factory already Mag-na-Ported so both stay on target rather nicely even with some of the heaviest recoiling, SAAMI specification, Factory ammunition offerings that are available from the Big Ammunition manufacturers.
It would be VERY difficult to convince me to give up either revolver. Unless you were offering me Stupid Money for one, then it would be no thought at all
I would feel the same if I owned one of the 686 Competitors instead of the ones I already have
If you have a line on a 686 Competitor at a fair price, I would go for it. I think you will like the revolver