in my opinion regarding the device provided by the link, it appears the main advantage would be an external antenna. where as most laptop and some desktop pcs do not have these... which would bring up the subject of increasing the sending and receiving capabilities of the 2 devices in question (from router to pc). i.e. beam shaping, like putting a hole in the bottom of a pringles can for the router antenna (if it has external antenna) so you can aim the signal more effectively at the intended target...
if it were me (which i have been in this situation) a wifi range extender placed in the middle of the 2 devices should boost the signal at the pc. however actual ping times should be measured both before and after just to find out how effective the real world result will be. for example, more signal bars but similar ping times would be a loser, no gain regarding real world gaming. test this by using speedtest.net via google chrome web browser. hope this helps...