Just upgraded myself to 9.1 without incident. For those doing the same, some comments:
-- Installer ran smoothly on main computer until last step, progress bar almost all done, when I had an (uncomfortable) 10 minute hang at the "Setting File Permissions" step. Just wait, it will eventually reach the "Installation Complete" box.
-- I don't (as yet) notice a real speed increase or decrease. Possibly, if I had uninstalled ver 8 and done a clean install of ver 9.1, I would have seen a speed up since ONLY new installs (not upgrades) install SQL Express 2012 x64. And why is this ?!!
-- My LabCorp & Quest, NewCrop and Updox interfaces were all reset to "inactive", and I received error messages. Can be activated in View>Administator Option>Interfaces
-- In the Sign Off window, when a message/reminder is sent, the subject line still duplicates the patient name & birthdate (see below). This bug Has NOT been addressed for over a year, when ver 8.xx was introduced. Very disappointing.

[Linked Image from amazingcharts.com]

John
Internal Medicine