The 800 series Z-Wave chips give you
better range in mesh mode vs the 700 series Z-Wave chip. This is why you see the 800 series range extenders.
Some people from Z-Wave did a test and where able to get 0.7 Miles range line of sight in Long Range Mode. Z-Wave is not dead - #120 by Hedda. I personally have been able to get 300ft line of sight in mesh mode.