Samba4 on SME is a huge task. But, even without considering SME (just SOGo + samba4) I personaly think native outlook connector in SOGo is not mature enough to be used in production.
I don't know for Funambol (Funambol connector on SOGo is working for BlackBerry devices, but I never tried with Outlook).
I know it's not possible everywhere, but you should give Thunderbird a try. With the various extensions (sogo-connector, sogo-integrator, lightning), it's really a great exchange+outlook alternative