I've been fishing them for the last 5-6 years in WI and IA and have fished them some back home in PA.
In a nutshell, the PS is an excellent fly in limestones so long as they have a little bit of that spring creek murk to them, or alternately, if they are up a bit and just slightly out of whack color- wise.
Otherwise, unless you're fishing small brook trout water, they aren't really that effective of a fly in your garden variety clear PA freestone. They're (for a similar example) pretty much of a bust (IMO anyway) on the clear freestones of WI's Sand Counties, WI's other major region of high quality wild trout fisheries.
I don't know, but I'd imagine they would also work well on relatively new stocked DH fish, especially RT.
The Coulee TU link posted shows the fly being tied on a conventional nymph/wet fly hook. It's been my experience that PS's tied on a scud hook are quite a bit more effective.
It is a real good fly though, especially on the front end of a 2-fly rig with a smaller olive nymph or whatever trailing. Probably work well on Spring Creek or any PA limestone with the "murk".
