I did upgrade the other day to version 6 and the upgrade managed to lose notebooks. On further examination, it was the off-live note books which were not carried over to the new version. Luckily I kept the old version so I transferred the offline notes to a synched notebook and then upgraded. Seems to have worked ok. (I could have exported the notebooks and re-imported them after upgrade.) Couple of points... 1. Why does Evernote checksum the contents prior to upgrade and then rechek the checksum afterwards? This would at least alert us to the fact that the new version was 'different' in content. 2. Even better would be a notbook by notebook comparison to highlught notes not transferred. Shouldn't have to do this but it seems Evernote has not been successful at performing faultless upgrades. 3. Without this type of checking how do I know whether the content I had before the upgrade is the same as afterwards?? 3. Off subject but the MAC version is the most boring UI I have ever had the misfortune to look at. I use Evernote extensively and need to have some faith in the product. Currently, I don't.