Should I enable Advanced Wireless options - Implicit BEAMFORMING, MU-MIMO and Fast Roaming?

Beamforming can be enabled. I use this. MIMO is for use with client devices that support MIMO as well, so if you have few or several devices that support MIMO, then you can enable this. If you only have one or two devices that support MIMO, then depend upon usage and operation, you may disable MIMO. I only have one device that supports MIMO so it's not really important. You'll need to contact the Mfr of your devices to see what is MIMO supported. Fast Roaming is for devices that roam around while you using the device. Some devices don't handle roaming themselves or not designed to roam while in use so depending upon the device, Fast Roaming may or may not be needed. Seen others post were it has causes some probems so they disable it.

Over all you'll need to try using these features to see what works best for your devices. The only feature I use is Beamforming.