Upgrading to 220.127.116.11 will not resolve the issue presented.
As found in the configuration guide of release 6.0 :
Controller software release 18.104.22.168 or later supports up to 20 controllers and 1000 access points in an RF group. For example, a Cisco WiSM controller supports up to 150 access points, so you can have up to 6 WiSM controllers in an RF group (150 access points x 6 controllers = 900 access points, which is less than 1000). Similarly, a 4404 controller supports up to 100 access points, so you can have up to 10 4404 controllers in an RF group (100 x 10 = 1000). The 2100-series-based controllers support a maximum of 25 access points, so you can have up to 20 of these controllers in an RF group.
We have the same issue and the splitted RF group causes a lot of false rogue AP alarms.
first you need to understand that mobility group and RF group are TOTALLY different things and they don't influence each other. These geoups only share a common name you put on the initial WLC setup to simplify the installation process. If it's easier for you to realize that, please change the name of ie the mobility group, to something different than the RF group.
Second the limitation is 20 controllers OR 1000 APs, therefore you need to count the total APs before someone concludes that your 7 WLC are not OK. You caould have 15 WLC with 20 APs each and your system could go fine.
My recommendation is that you should move to WLC version 7 as this includes more cool stuff and prepares your environment for clean-air.