Yes - I have installed and had a look at Openchange and SOGo. I am wondering if using SOGo is going to lock me into using Openchange exclusively, or if I can use it to access my other calendars and address books. At the moment it does not seem I can.
On 3.3, Roundcube could access the Zentyal server address books, email and calendars without modification. After upgrading, it could not. It also has plugins so I could sync with other calendars and address books.
Seems to me that Openchange / SOGo are a bit of a backward step. Instead of letting you use Microsoft's protocols as well as the open standard protocols, it is replacing them. If you want to do that, you might as well use Exchange and be done with it.