Based on the review posted, there is still no way to natively transfer files other than the web interface. The reviewer is a developer so he should know what he is talking about.

This is the only other method I've found: https://github.com/nick8325/remarkable-fs

You'd think scp would work also but I haven't found info on the subject and I don't own the RM1 to try.

edit: found someone's scp script: https://github.com/reHackable/scripts/blob/master/host/repus...

The changelog is public so you can see the rate of development if you're interested: https://support.remarkable.com/hc/en-us/articles/11500546010...