To 365 or Not To 365

The network in question is currently running a single exchange 2010 box and we are looking to install another in an alternate site. This brings up the question as to move towards 365 or not. Now we want to preserve single sign on, which then brings up the ADFS and DirSync scenario. I am keen to hear what people think or if they have had experience in delivering the ADFS and DirSync solution. 

Thanks