I recently went from 9.1 to 10.1.1. The upgrade went well, no problems with the database, all nodes are still there, no errors.
HOWEVER!!! The engineers who put the latest version together forgot one small detail that they hopefully will get fixed for me soon. If you have Orion installed on an application drive that is not C:, the collector service will not stay running. So keep that in mind when you install it. I also noticed that the SQL DB is constantly unloading now with memory problems, something it wasn't doing before, so I have to go back to find out why.
Thanks for posting this detail here. I'll mark your post for development and PM just to make sure they know about it.