@Ka6uka -
ive had 3 MX4300 AP with wired backhaul, and a 4th AP with WDS backhaul, runninng for months. for my space, with about 5 fixed-location stremaing devices and many devices that roam with less-demanding bandwidth requirements, i've found the most reliable consifuration to be on the FOSS drivers. i htink the things that interfere with client function are more typically lags when moving around, which depend on band-switching and roaming.
the NSS builds typically have a little faster raw transfer speed, but i have yet to overcome the issue of undesired client isolation, where wirelss clients can only see the current AP and upstream router devices.
i've tried DAWN to help with roaming but havent found a big advantage, and that would depend on overcoming the isolaiton issue with NSS builds.
i've tried new NSS builds (on qosmios'basic) every week or so but my limiation is the client isolation, and the many tricks in this long thread have not been continuously successful for me.