This is just a heads up on what I plan to do next. Having gained some familiarity with the inline LMs adding support for sub/superscripts seems like a useful feature to me. Actually the scope of this is a bit wider as to do that properly and not as a quick fix it involves support for the set of alignment properties (7.13) and the matching correct building of line areas (4.5) and inline areas (4.6).
I'll put my thoughts on this into a wiki page over the next few days. Manuel