I have finally had enough, and am moving to WordPress. This means that recent (in the last few hours) comments won’t be picked up in the import/export (and none forward, until I get the new site up). I will try to pick up the stragglers after I deal with the upgrade in general, but will make no guarantees. I’m a little frustrated, because MT 4 decided that any comments issued before I upgraded to it are unworthy of being exported, so older posts won’t see the older comments, unless you find them via the older URLs. And of course, you won’t be able to comment on them, because they’re static web pages.
I’d pay something to someone who has software to merge old with new, but not a lot. On the other hand, there may be a lot of folks in my situation, given the Movable Type disaster…