In 1981 or 1982 I switched my department's patrol division (which I then commanded) over to 4" S&W 686s. They came with target stocks. Many of my troops replaced those with nylon Hogue Monogrips or Rogers (later Safariland).
Smith was only supplying the no-dash 586/686 with their own target grips as far as I ever knew. At this time Hogue did not yet offer their Monogrips in rubber. Once the rubber ones did become available, I still stuck with the nylon models. In my opinion that stippled surface was (is) the ideal gripping surface. Sufficient traction to maintain grip stability, but not so sticky as to hamper adjusting one's grip on the revolver.
Shortly after we had purchased the 686s, I scored a high Patridge front sight 6" 586 (which would allow for a neck hold from the 50 yard line, very useful in PPC competition). Those one also came with the Smith target stocks.
I have read many incidents of rust forming under rubber grips, even on stainless steel. If for no other reason, I would avoid them. Some can say this is not so, or it can be avoided with preventive maintenance, but I see no benefit from the risk.
