I'm using Kolab Now across several devices, iPhone, MacBook, iPad and PC at work, three of which connect via Activesync.
I frequently create mail folders all the time to manage my mail, but the inability to have all my folders on my Activesync devices without me having to go into Roundcube and tell it to sync that folder to other Activesync devices is greatly frustrating.
Given the fact that you charge extra for Activesync, I would expect this feature to be at my disposal should I choose to use it. The lack of it a hamper on productivity.
Activesync needs to be the way of connecting these devices as they require push.