I did forget about those, the MU-MIMO in the UAP-AC-HD is pretty sweet for a number of high bandwidth devices on your network and this is a nice upgrade from the UAP-AC-PRO. I read about the release of this and remember a huge difference being the processor(s) in the unit allowing for reliable connections to hundreds of simultaneous clients in commercial environments.

I read about the UAP-AC-SHD when they landed in the Beta Store a few days ago. Seems like effectively an UAP-AC-HD with an additional radio for real-time spectrum scanning, finally trying to match the feature set of Cisco Meraki (AMP) and Ruckus (Cloudpath and SCI). The additional radio should in theory allow some decent auto-configuration too.

No hands on experience with either of those but interested in playing with the SHD, maybe I'll get one...