Where I come from(Upstate NY) the Quill Gordon is know as "The Iron Fraudator Subimago". And since the Nymph is basically inactive(hangs out under Downstream side of rocks and then leaves it's shuck underwater) the nymph is of no use to a fisherman only a wet fly pattern is needed.
As far a Ephemeralla Subvaria or Hendrickson: The Female Hendrickson is called Hendrickson and the Male is called Red quill. While you Don't need a different nymph for each gender you do need a different pattern for dry flies;hence the two different names.For dry flyfishing the males and females will hatch in different areas and the trout are selective when choosing the Male (red quill) or the female (hendrickson). And yes hares ear nymphs,pheasant tail nymphs will do a decent job tied in 12 and 14. There are some killer emerger patterns that we use locally also.
As far as the Blue quill nymph that the author is refering to tied on a 16,I Don"t bother with in here in upstate.If The Gordons have not hatched yet usually the fishing is rather slow and not worth putting your waders on,but if we do go out we usually catch a few on a prince nymph or pheasant tail tied in 12 or 14