When I moved away from WordPress, I didn't try too hard to bring over my old blog posts. I don't post that often and the interesting stuff (like recipes and stories) all have their own links anyway. But I felt like I was practicing revisionist history to remove all the old posts. True, they're probably out there somewhere, but no place where I could get to easily.
I had the old WordPress database dump that I took before I replaced the site. After some (okay lots) of fighting with the dump file, I got the posts into an sqlite3 database that I could write Python scripts against. I pulled out the contents and wrote them into the format Poole can handle.
There are a lot of rough edges in the results. I'm guessing many of the links won't work right yet. But, the history is there now and I feel strangely better about that.