It seems that ZigBee Alliance found a way to make its technology more popular. And that way is using alternative energy such solar or some other stored energy sources to power devices. That what EnOcean does a long time.
Actually using green battery-less devices is good. But as I know the real problem with ZigBee is weak interoperability between devices from different producers. Maybe Control4 which is going to switch to ZigBee Pro, will produce whole range of needed devices. But for the DIY enthusiasts it’s a real problem. The Z-Wave looks more attractive because all its devices are interoperable. Also the model range and price of Z-Wave devices became better and better in Europe. The cost of some of them is near to X10 devices. So, in my mind, ZigBee Alliance should work on it. Of course, if its target is not just cover Control4 needs.