Hi I heard that cnPilot roaming does not require a controller (unlike Unifi). Is this true? Can you shed some light on how it works? is this like Aerohive? and are there any special licensese now or in the future?
Yes!
Here is a post the explains it.
No controller, no cost 
http://community.cambiumnetworks.com/t5/cnPilot-E-Series-Hotspot-E500/Know-about-Enhanced-Roaming-feature/m-p/54277/highlight/true#M27
Hi,
Yes Cambium cnPilot E400 / E500 and ePMP 1000 Hotspot support Controller less roaming. When wireless client autehnticates with the AP say AP1, AP1 will inforrm about wireless client credential information to other Cambium APs which are part of the same VLAN network through Cambium propreitary layer 2 multicast packets. When client moves to AP2, AP2 will be having credential cache for the client, it can skip authentication and move client to data ready state.
Controller less roaming is supported for EAP 802.1x authentication and also Captive Portal authentication. Hope this will calrify your doubt. Please drop a unicast mail if any further information is needed to me on channareddy.ireddy@cambiumnetworks.com
With Regards,
Channareddy