Whoa! That's a lot of subnets... A couple of questions:
1. Are the clients actually roaming between these local controllers? Does it happen frequently or are they separated by some physical distance?
2. Looking at this from a bigger picture, perhaps it may be beneficial to take a look at re-architecting this WLAN space to a "flatter" type of design...again, not trying to push you in this direction...just making some initial thoughts on the info above.
Can you provide more insight into your topology and design?
Thanks!