Ghost--I found your remark about taking umbrage regarding a "Ph. D. in dry fly fishing" interesting because I strongly agree. I simply feel it is impossible to reach that level of "educational" achievement when it comes to fishing for Park trout, although it may have been, as you hint, nothing more than a way of hyping a product. For my part, after 60 years of fishing Park streams, I'd like to think that maybe I've reached the kindergrten stage or maybe just a tad higher. The key to the whole matter comes in my favorite quote from Horace Kephart's writings: "In the school of the outdoors there is no graduation day." That certainly holds true when it comes to fishing for trout in the Park.
One other thought. For years I was almost exclusively a dry fly fisherman, although I would, once in a great while, dabble with nymphs. Now I almost always fish with a dry fly and nymph dropper, which gives the best of both worlds and produces more fish. I haven't done a scientific study in terms of counting numbers, but I'd guess that somewhere between 60 and 75 percent of the trout I catch come on a nymph.