Orbi RBR 50 New firmware v2.0.0.74: Can you enable MU-MIMO, fast roaming and Beamforming now??

My own experience has been that Orbi is OK with implicit beamforming (IB) and MU-MIMO (MM) "On", but my setup is better with both off.  Your mileage may vary - I suggest experimenting and seeing what's best for you.

In my case, I don't any older wireless devices (i.e. non-ac) that would benefit from IB, so I generally haven't ever had that option enabled, outside of doing some gee-whiz testing.  

I don't have multiple MM devices, so I wouldn't benefit from having that option checked, so I don't have it enabled.

As for Fast Transition (FT)...  I tried that when it foist rolled out with the 2.0 firmware, but I experienced quite a few drops with my wifi-calling, so I now have the FT option unchecked too.  

In my setup, most of my house has some overalp between my router and sat unit, so i think the having the FT option enabled just caused my iPhone to constantly jump between the router and sat.  I'm fine with my phone being "sticky" with whatever unit (router or sat) it wants to be sticky with, so FT does more harm than good for me.

I don't have multiple sat units, so I have no interest in the new mesh option (that's the "Daisy Chain"option in Settings).  I disabled that option, since it seems to be enabled by default.

But if you have multiple sat units that have problems connectimng using the current "star" topology, then the Daisy Chain (mesh) option is certainly worth trying.