Getting back to the original post on the thread - for the home market, I'm not seeing this as a must-have or needed feature - e.g. don't go out of the way to choose a device or AP just because of MU.
If it's there - give it a try, but know that like mentioned, even with just two MU capable stations, it's going to be hard to notice any difference, and there can be a hit on performance depending on client chipsets and the AP chipset used (including firmware for that chipset).
In my experience - MU is best for devices that don't move around - so desktop, set top boxes, maybe... devices that move around like tablets and mobile phones - MU isn't helpful there, as the sounding matrix needed for beamforming and group membership decisions for the MU frames incurs a lot of overhead and airtime, and this can impact performance, even for the clients that are not MU capable.
The engineering effort to make MU work in WiFi is pretty impressive - I'm not knocking the technology - if one looks at the math alone, it's a big step in processing requirements in real time - and that also contributes to better SU performance if MU is disabled. If one looks at the earlier AC1900 Wave 1 AP's, the current crop of AP's on Wave 2 silicon do perform better, and the results generally show, even with older client chipsets.
