All of your criteria Dynalist meets, though 2 not so directly. 0. This is subjective, but Dyanlist meets this for me. 1. You can export your data from Dynalist

All of your criteria Dynalist meets, though 2 not so directly. 0. This is subjective, but Dyanlist meets this for me. 1. You can export your data from Dynalist as txt or opml 2. While your data isn't exclusively stored there, you can set a backup of your Dynalist data to Google Drive or Dropbox. This works for me.