Another update on this issue - the users continue to get disconnected. My support guy at Extreme has been feeding me with ideas on adjustments and some ways to get better logging. Still, I can't ignore the fact that there are a lot of users of laptops that shipped with Intel Dual-Band wireless NIC's who have this same exact issue ... and some of these date back to 2012.
To try some Intel community advice, this morning I disabled the a/n/ac radio usage on all cards, disabled the "allow this device to sleep" on the drivers power options tab, and also disabled all power saving of the PCI-e slot in the OS's Power Options. Seems kind of lousy to castrate my users to lower speeds. But honestly, they don't need the bandwidth. All they run is a single web-based app, and an in-house instant messenger.
So far - I haven't seen a drop all morning. I am cautiously optimistic as I await user feedback and hawk the event logs!