If you actually think this twice, no other Nokia handset device has had the opportunity to actually upgrade the OS. Why they should even provide this option in any case if there are serious QA issues to be considered to ensure smooth transition to MeeGo/Maemo 6?

If you want your MeeGo on N900, support the community behind it instead of spreading the FUD. Even if it takes some extra steps to perform a OS upgrade on development snapshots. Embrace what we have now, Stskeeps, Harri and rest of the folks are doing a tremendous job on ensuring compatibility with N900 for MeeGo. Be sure to thank them later on.