I would not upgrade to until 7.6 comes out unless you have a need to. We installed the 7.5.1-028 upgrade and it "broke" one of our filters. It was flagged MS office attached as a compressed, zipped and placing them in quarantine. It gets fixed in 7.6 but it's not available for General Release.
We upgraded to 7.5.1-102 earlier this week and so far have not had any issues. As Doug mentioned 7.6 is finished but not available yet. So unless you are having issues with your current release you may want to wait for 7.6 to save some extra work.
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...