How much will the flavor of the Appendix N books really color the game? Take the cleric for example. Its a staple of D&D, but I'll be damned if I've ever read of any character in a sword & sorcery book that sounded like one. Priests yes, but none that wore armor and used maces. And hardly any that healed anybody with magic. The priests are usually more like wizards than anything else. I'm hardly an expert on the books in the list, mainly having only read Leiber, Moorcock, Fox, Tolkien, Lovecraft, and Howard from it, so are there really clerics in any of the other books in that list or does it come mainly from Gygax's medieval and catholic readings?
Oh, and another thing that has always bugged me about the difference between D&D and s&s books- fighters are effective in the stories even without armor. Conan usually only wore armor if he was going to war. Try going without armor in D&D (any edition) as a fighter and survive. Will the new game do anything to make this possible?
Actually I'm reading the Conan series and in several stories it mentions his shirt of mail worn under his clothes saving his life. In one I even remember him lamenting over the fact that if only the rest of the men had been wearing armor more of them would be alive right now. So I think he wore it whenever possible. However much like D&D Conan was breaking out of captivity a lot and having to fight with no armor on. I think this made him an even more impressive hero than your average adventurer.