It went like this:
- entered username password, hit import. The system did nothing.
- 4 hours later I refreshed the page, got a "It was interrupted, continue?", I hit yes
- it now started and grabbed the first 100 posts after which it gave the "Oops, livejournal disconnected us" error. This apparently is the handled case for ixr getting a 406 error. WordPress recommended waiting 30 minutes, I gave it 40, then an hour, both times I got the same response.
- I deleted the import, and restarted from scratch. The results were exactly identical.
- out of curiosity to see if the mass export functionality was bollocksed, I installed a windows lj backup tool and ran that, that worked fine.
I'm game to try a different approach if you want to test something.