Just thinking that the current arrangement can be a bit awkward. Depending on how many posts you select for splitting, the submit button can end up floating around sorta halfway down the page, which means you then have to go looking for it.
It might make more sense to do the template much like the error log is done: with duplicated submits top and bottom, that are always in the same place and easy to find. Works well for the error log, so I can't see why it wouldn't work well here too. Code changes required are very simple.
I dream of a world where buttons are always available inside the viewport.
/me runs