Concerns you have, however, the 5GHz band while the much less interference than the 2.4GHz band, the coverage however, a lot less. In a house of routers mostly depends (in my Fritzbox 7490) in the basement. In the basement room I have of course the full 866mbit, before the basement there are still 780mbit, the entire basement (basement) it varies between 500-700 Mbit. On the upper floor it sags already, here are max. 300Mbit possible.
That's just, unfortunately, that way. Either you hang the Fritz box in the living room (with me almost impossible) or one waits for AC-enabled repeater, which then may take corrective action and allow a faster speed in the upper floors.
The card is certainly top of the price.