Wireless roaming from Cisco to Aruba

We're starting to replace our Cisco wireless LAN with Aruba, starting with our new building that's finishing soon. There is a connecting hallway from older building, I'm wondering what happens when wireless clients move from Cisco network to Aruba. How smooth is the transition, if we drop the clients to same VLAN on the controller side and use the same RADIUS servers (Clearpass in our case)

There are some special devices like some self driving forklifts that use wireless, not really sure though how they communicate.

I can test this once the building completes but I'm curious if anyone has experiences with this. Is there something we could configure to make the roaming better? There are some 802 standards for roaming but I'm guessing those are used when the different wireless networks terminate to different IP subnets?

Thanks for any ideas!