My general rule of thumb is that if there are features in 8.x that you need now then upgrade to it. Otherwise go with 6.3.6. You can also find our Recommended Software Releases for VOSS / VSP 8600 at https://www.extremenetworks.com/support/compatibil...
Software Lifecycle Policy document contains EOS/EOL information on the OS. End of Sale End of Support document contains EOS/EOL information on the hardware. Hope this helps.
