Now I realised what 'Display plain text' does, I had to switch back off because I need the formatting.
I don't run Nvivo on a network but the file is stored in a Dropbox folder for added backing up. If that complicates things, I can keep the master .nvp file in a non-Dropbox folder and create copies on Dropbox.
I do appreciate that autosaving huge files may not be a good idea, but some sort of incremental autosaving may be efficient enough. At the moment, reminders are just annoying and switching them off is asking for trouble, particularly when the setup is not very reliable.
For now, I just hit Ctrl+S every few minutes and I will keep my setup hoping Nvivo won't crash. So far, so good.
Incidentally, given the potentially sensitive nature of the data, encrypting the .nvp file on-the-fly, particularly when it is stored on the cloud, will be great. I know we can use third-party encryption for that.