Upgrade to 7.6 question

Hi all,

I have a question about upgrading of the quest vWorkspace farm. All our Quest servers are rudundant.

When we start to upgrade our farm, is it possible to run in a mixed environment? like one connection broker 7.2mr1 and the second one 7.6? or both connectionbrokers 7.6 and all other servers 7.2mr1?

Because we have customers that use the environment 24x7, and we want to minimize the impact of downtime?