[Zope] Zope 2.7.8 or Zope 2.8.X

We have been running on Zope 2.7.6 with a few patches. I am now planning to migrate to Zope 2.7.8 but am pondering the move to Zope 2.8. We are in a production situation and cannot accept any downtime, so I am very concerned about stability and compatibility. Can the list provide words of advice?