I’d push back a little here. Fishing a 20’ stream in Montana located in a sprawling meadow, with constant wind, and 20” trout isn’t exactly the same as fishing Falling Springs.
Not trying to be argumentative, just providing context to my original question.
I agree with this, but Falling Spring is likely closer to that than most PA streams only because it has meadows and some large trout.
The majority of PA wild trout water does not.
Your post 17 IMO is accurate. However, while I think a 8'6" 4wt medium action does more closely match what we have in PA compared to a Sage X 590, that IMO is still a bit long when you consider the majority of small wild trout streams in the state.
This is all preference and opinion. Some guys like long rods for small water. Everything is trade offs. Advantages and disadvantages to either.
I still think a 7'6" 4wt when considering all wild trout water in the state of PA as a whole, is the most practical rod.
This said you don't need to own just one rod, but always consider where you fish first and take what you deem as most appropriate for the situation. For me, most my fishing is on small streams, brushy, in the woods with small wild trout. I mostly use a 6'6" 3wt glass rod. It's comfortable to walk with, fish fight nice, it's fiberglass so very durable, 3wt delicate short casts but little to no wind.
It's what I like for those streams.
But id grab an 8'6"-9' 8wt and toss articulated streamers on Penns or the Lehigh too.
So there is that.