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.
Oh one other thing people are saying about 1.7.9 is that their getting the "lots of interference" with the new firmware. That's also not an issue for me.
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.