I've guided hundreds and hundreds of clients over the last few years and very few of them had the tool that we call the nymphing rod in their arsenal, very few. Now, did they use the techniques that we now label as nymphing? Yes, when the circumstances called for it. Were they hampered by using the wrong equipment? No, not really. I will make this statement: the average well designed graphite fly rod of around 9 feet for a 4 or 5 weight line that is moderate to medium fast will be able to do everything that you want it to do, including all forms of nymphing, and will only be restricted by your ability to use the rod correctly.
As Tom Dorsey said, this sport is about fly casting and your garden variety nymph rod is not a good casting machine. A stiff butt and mid section married to a soft tip section gives an awkward, hinged feel when you need to make a long cast instead of just "flipping and mending". I have a 10ft, 4wt nymph rod given to me as a gift. If all that I wanted to do was nymph I'm ok but longer casts to rising trout felt like shooting a bow with an arrow of the wrong spine. There was less control over the placement of the fly as my casts got longer.
My other graphite rods of between 8 to 9 ft can do EVERYTHING that my 10 ft nymph rod can do PLUS make long accurate casts. Am I hampered by a shorter rod?? I can bounce nymphs on the Swift, the EB, the Millers and the Ware and I can position myself to cover all of the water correctly (sometimes nymphing) with a generalist rod of 8 to 9 feet. Am I hampered by not having the softer tip section for strike detection? ARE YOU KIDDING ME??? There's something wrong if you can't detect a strike while nymphing with a generalist graphite rod. John Gierach, the great writer, once said you could nymph fish with a broom handle. Get the point??
I read recently that instead of shelling out $700 for a new fly rod the angler should buy one for $250 and spend the rest of the money on casting lessons. Good advice?? I think so!