Ok, I looked at all the answers and with the apparent death of WPExport there does not seem to be a useful solution, which is just completely insane. It seems impossible to me that no useful WP-WP solution exists, but that seems to be the reality.
I want to export posts from one WP blog and append them to another. I want to keep Authors and I want to correctly keep multiple categories. I want to keep comments.
I would be willing to go WP -> MT -> WP except WPExport is broken and does nto seem to handle multi-category posts and the other WP exporting script doesn't handle multiple categories.
As I find it unlikely that no one has ever had to make this work. Does ANYONE have a solutiont hat they know works?