Having good RF coverage is important. A slight blip when you roam is usually
acceptable, but not if it's seconds. Apple clients tend to be stickier than most,
so we often reduce coverage/data rates, even apply a new 'smart-roam' feature
in 9.7+. Don't use rate limiting. Here is a suggestion to apply to your WLAN,
thru a ZoneDirector CLI (so SSH, and login with admin credentials).