Just to clarify, since a few people emailed about this... I'm somewhat fond of the markup, and think the strength of the system is in fact that the markup is fairly simple, there's a small amount of it (contrast that with many of the open source Wikis, a big mistake IMO), and that the learning curve is very reasonable - small amount of very common stuff, with the rarer and more esoteric stuff being there but more self-contained. I've been pretty stubborn about not extending the markup because of this, or at least not the more simple end of things.
While quickly learning how to do this does not in practice seem to be an issue for most people, its also true that there's always going to be some subset of users that would be unable or unwilling to approach a system that uses a markup style of editing. I can't quantify how large that subset is, or how important it is for what I'm trying to accomplish. While I don't believe not having an answer for that group is terribly damning for me, other things being equal I'd still like to have some more options here.
