I used the Linksys PLK300 (AV200) for 5+ years in a house built in 1965. Not the best of speed (<20MB/s in file transfer, enough to play 1080p MKVs off Windows file sharing) but it is absolutely stable compared to the weak and often interfered wifi signal. Recently upgraded to the TP-LINK AV1000 kit and I got about 3x increase in file transfer. I can't recommend Powerline enough if it works in your environment (I have heard detached house works better?).
What I am not sure is if you get a Powerline kit that is a wifi extender on one end, how good are their wifi capability?