Erich, I’ve been working on one for this blog. No persistent cache to speak of except for the files themselves when their sources haven’t been touched, and I haven’t found any reason to need XML, but I was trying to avoid much of the same nonsense you mention. As such, the templating is as dumb as possible. Perhaps you can do a lot more with XSLT, but I didn’t find it very interesting. Templating systems in general make me itchy.

I am now, however, thinking about making it easy to subclass that part of things as well, which could be interesting. Write something to talk to the big XML library, one import in layout, a few lines to save the cache in a pickle... hmm!

(I always stick a “raw-html” role into reST if I really need it for something, but generally, I try not to think about HTML period.)

I haven’t heard from anyone about it yet so I don’t know which X, Y, and Z are obviously lacking. :)