For RT-AC87U owners: I did a quick recompile of the firmware with the newest Quantenna SDK taken from the recent Asus release (since updating the SDK was a fairly simple thing to do). Grab it here:
http://www.mediafire.com/download/5z5zlb4z6yz412e/RT-AC87U_3.0.0.4_376.49_5_newqtn.zip
This uses the new Quantenna v36.7.0.31 driver which should resolve compatibility issues with Apple devices. Asus recommends doing a factory default reset when updating to this new driver - I suggest people first test it without doing so. If you still have connectivity issues with your Apple devices, then go ahead and do the recommended factory default reset + manual reconfiguration.
Been running it on my own router for the past few hours now while using the laptop connected over 5 GHz wifi without any problem.
You're awesome. Thanks! Happy new Year!