Unfortunately, evernote is interesting example of very strange behavior - when they become in troubles with slow backend written on C#, they switched to C++. T

Unfortunately, evernote is interesting example of very strange behavior - when they become in troubles with slow backend written on C#, they switched to C++. To be honest, I cannot say anything about e-note client quality, I have not used it at all (I try to use opensource self-hosting alternatives), but such solutions on backend side, look very odd for me, and not look trustworthy. Returning to your case, at adequate services, should be possibility to backup your documents yourself, or service should have incremental backups. So, in such circumstances I will first figure out, if it is possible to make backup myself (and will do backup; and will plan backup frequency based on value of day work for me - for most valued - daily or even few times per day; for less valued - weekly). If self backup impossible, I will ask tech support to return to previous state on server side. For alternatives, as I know, e-note is best for its cost per client, I think anything else will be more expensive (unfortunately, self hosted FOSS solutions are more expensive, even considering, I trust them much more).