we switched from SR8 to SR9 because of various Inputfield Bugs fixed in SR9.
Sadly we encountered another possible Bug in SR9 then (already forwarded to Qlik's R&D Team (ID 69613))
which is closing an open session if a reload of the same document is performed in the Background.
This happens if you open a document with the "open in Server" Option with the Client.
So in this case I would recommend you to stay on your current release...