In one of the last hard copy catalogs I received which listed 3rd gen TSW's, they showed the integral rail models available in the full-size 5906/4006/4566TSW's. They were the "standard" model available for order at that time ... to existing LE agency customers who were already carrying S&W 3rd gen duty weapons.
On the other hand, they were also still making & shipping the original TSW full-size guns made with the riveted rails. Agencies were offered the choice of either type of frame rail.
Although I have no interest in having a frame rail on my own guns, I think the integral rails are "cleaner" in appearance. You'd think the integral machined rails might be stronger than the lightweight alloy used for the riveted rails, too. I've seen upwards of half a dozen broken rails on duty weapons made with the riveted rails.
I wouldn't be surprised to see small numbers of the machined rail guns reach the "trade-in" market at some point, especially as we're seeing increasingly more 3rd gen guns being replaced with M&P's.
Me? I'd still be willing to buy that
never-produced-but-wished-for all-stainless steel 3916TSW.

Yes, I'd probably be willing to pay $1000-$1100 for one. Maybe.
