I have no issues myself with 1.7.9 but I've heard of a few people having range issues. I have what I thought was the REAL argtek range extender but it's a fake and my range is still great 1000m city-4000m open fields. I also did the 27dbi wifi boost so I never lose video.
Works good for me, have my max distance to date using this new FW, over 4000 meters with RC mods. The only issue I had, but now it's gone was the "strong interference" message. Started loading the Go app last, after all the equipment is powered up seemed to fix that.