I need to ask that how much time is taken in WiFi roaming (switching between the APs). I am asking about Cisco APs, Cisco outdoor/industrial routers that can connect more than 1000 people, and any other company you people know.
With a controller to coordinate the associations, handover is very short in order to keep voice call quality acceptable. Aboslutely not for 1,000 users but without a controller you can see 1 second dropouts routinely. Badly organised controllers in public spaces can easily be observed to drop out for much longer, perhaps 30 seconds.