Yes, it seems like it might, although I don't think it would help for the situation I have. On the other hand, another recent thread on this list (http://markmail.org/message/zwyx47gqrovpi4fc) makes me wonder if I shouldn't take another look at CodeInjector. For some reason when I first looked at it, I didn't think I would be able to do the rewriting I wanted using that, but it would be nice to avoid having to serialize and recompile.
This is what we have implemented to, but just for XPath now.
Would make a nice addition to Saxon itself I think.