I'm confused. I'm about to upgrade a 5508 controller so I can do the pre-download to the access points, but in every doc I find, it says to disable the WLAN's before upgrading. This makes no sense. I'm just moving code over, why do I have to disrupt my wireless network in order to move code?
It's kind of an old legacy of the older documentation. No real need to do it anymore.
I too never disable my WLANs, but I know what you're talking about how it is suggested to disable all WLANs and your b/g/n, a/n networks, per the documentation.
After performing numerous upgrades across multiple platforms, I have seen, very infrequently, that WLANs may map their interfaces back to the management interface after upgrade/reboot. I'm not sure if this was a particular release x to release y issue, but perhaps this is to help prevent this?
Regardless, nothing "bad" should happen by not doing it; just double check your config once you bring it back up.