The solution was easy.
Evernote lets you set up a folder to monitor which will import anything you put there.
Keynote allowed me to export all my notes as rtf files into that folder.
Bada-bing-bada-boom and Bob's your uncle.
At a bit of a broader level, this sounds like all your notes ended up exported "flat" - without structure. Or did the "monitored folder" also monitor all subfolders and retain structure?
I am a fairly interested participant in the Battle of the Notes. My eventual solution was MyInfo. Basically, I don't get too fancy with the data proper inside the notes - structure and export make or break it for me. (If I ever needed to, import is in the same theme.)