We've recently upgraded our router to the Asus RT-AC86U, which supports MU-MIMO on the 5GHz band.
With our previous SU-MIMO router, it was my understanding that one slow device (e.g. an old iPhone) could slow down the wireless speed of faster devices on the network. This was problematic given the very large local file transfers I do wirelessly.
I think I understand the benefits of MU-MIMO and separate spatial streams where both the router and devices support it. However, I'd like to know if older SU-MIMO devices will negatively impact performance of other devices on the 5GHz MU-MIMO network (so should be restricted to the 2.4GHz 802.11n band)?