After several weeks after the upgrade of a (multi-country) site from Osclass 5 (Mindstellar) to Osclasspoint 8, here are some facts.
1. Problematic update, several errors during the update, some minnor, some major, some impossible to follow.
2. The final site updated works but with several issues, that need to be fixed. Some can be fixed, some can't.
3. The major issues are related to the Countries (Locations). If you have more than one Country, then the issues are worst. Several DB fields are added but are empty, like some coordinates for example. There is NO way to fix that, but to remove the country (the ads are gone) and re-install the country from Osclasspoint DB.
4. The USERS db seems to be working ok after the upgrade. I found no issues.
5. The compatibility of Osclasspoint 8 with old/legacy themes and plugins is so and so.
So, i would advice against doing that (Mindstellar->OsclassPoint), unless you are an experienced user or webmaster with Osclass and databases in general.
If you want to do the upgrade, then the best path is AFTER the upgrade to delete the country (or the countries) and re-install them from Osclasspoint DB. That way you will keep intact the users DB but delete all the ads.
I hope i have helped some people that want to move on with their site.