R350 Poor 5GHz performance 200.16, 200.17

[gritech]

Has anyone else experienced poor 5GHz performance on R350 APs on 200.16 and 200.17?  I briefly tried the 2nd version of 200.16 and both the initial and refresh of 200.17 with the same issue and went back to 200.15. However, I can't stay on 200.15 forever once security updates stop for it (they probably already have).  I have only R350 APs - 29 APs, ~200 concurrent client devices.

On both 16 and 17, I end up with estimated 25+% of my clients on 2.4 (normally only a handful of devices arriving/leaving the building) and those that are on 5GHz are at a lower data rate.  Also I received a lot of complaints about devices constantly disconnecting on 200.16 and all was fine when reverting to 200.15.

ex. an iMac that is stationary:

200.15.6.212.20:  AP Tx Data RateMCS 9/80/2 / 866.7M bps
200.17.7.0.152:  AP Tx Data RateMCS 7/20/2 / 144.0M bps

I have all channels manually set, but since the initial 200.16 release had issues with manual channels, I also tried auto channeling with no improvement.

I do not have band balancing or load balancing enabled; the clients overall do a great job of staying on 5GHz on 200.13, 200.14, and 200.15 also showing there is something off with 5GHz on 200.16, 200.17.

Another issue: on 200.17.7.0.152, when an AP is rebooted from the GUI, it goes to "upgrade required" instead of rebooting and gives the option to upgrade the AP.  However, the AP comes back online fine a couple of minutes later with no intervention.