Try nxhtml if you haven't already. Its "better" than mmm for some uses. What I really should do is figure out a way to open sections of text in their own buffe

Try nxhtml if you haven't already. Its "better" than mmm for some uses. What I really should do is figure out a way to open sections of text in their own buffer (and corresponding major mode) so that changes in that buffer would be reflected in the original selection.