Upgraded from 6.6.7 --> 9.0.0 beta using self install March 12, 2016 and have had no problems.
Windows 7 Pro Peer to Peer network, 7 computers, 1 provider, 3 active users at a time.
I had Amazing Charts Guardian Support ready on speed dial, but miraculously had no issues.
At ACUC 2016 they said they put a lot of work into streamlining the upgrade process and I believe them.
Happy so far.
Josue, I use Quest import interface and fortunately have not seen the errors you describe (yet).
It really is nice to be able to set up auto download of labs, and not to have to rely on someone to do this task daily.
