We finally deployed 6.5R2 last week and it has been an outstanding success.
In the week since the upgrade we've only received a handful of support calls in which we were able to quickly walk the user through the difficulties they were experiencing.
We now have ~ 700 clients running Windows XP, Windows Vista, Windows Vista 64-bit, Windows 7 64-bit using a combination of Network Connect, WSAM and JSAM all without any issues or problems. I can also confirm that the previous issues reported with Norton 360 Antivirus, and ESET NOD32 have been resolved. I have not had the opportunity to test Zone Alarm or Symantec Antivirus (Corporate Edition).
I'm really impressed with this release, unfortunately I came after many months of pain with 6.5R1 which will leave the Secure Access product with a black eye for sometime to come.
Cheers!