First impression of the coverage are pretty good. At the far end of the flat, this seems to be around on par with Ubiquiti AC Lite (Wifi 5), if not bit better, after a short bit of testing. hAP ac2 was useless here.
Depending on the country set, the TX-power might be different. (It is for Europe/ETSI). The classic MT driver is using the non-TPC EIRP limit, while the wifiwave2 driver is using the TPC-EIRP limit, like other brands and drivers do. The non-TPC limit is 3dB lower than the TPC limit. And for Europe, the EIRP limit is the TX power limiting factor. http://forum.mikrotik.com/t/wifiwave2-expected-performance/160075/1
For some countries the EIRP table might be just wrong: http://forum.mikrotik.com/t/removing-wi-fi-country-lock-using-netinstall/160149/1
Usable coverage depends also on the TX power of the client device and the antenna gain of the AP, for a good received signal.