Earlier quoted context omitted.
Lutron devices don't form a mesh network, though? And a limit of only one range extender. And only 50 devices? http://www.casetawireless.com/Pages/faqs.aspx I'll stick with Z-Wave, even though it's not perfect. And it's true that there's some terrible Z-Wave hardware but there's also better (and pricier) gear.
I've tried both Z-Wave and Insteon, and have settled on Insteon. It forms a mesh network over both powerline and RF and it's been extremely reliable so far. With Z-Wave, I had quite a few range problems.
If you get high quality devices across your whole network, it works great. It's fast, it's reliable, and it'll work over pretty long distances with the mesh networking stuff.
But even one shitty device can bring a whole network down, not to mention that you tend to gamble the first time you buy a device if you are gonna get a good one or not.
Things are MUCH better now if you stick to zwave-plus only as the zwave people are taking a much more "hands on" approach to ensuring that you can't sell garbage with the zwave name on it, and they've added a ton of really nice improvements to the system.
But unless you are just starting out it's gonna be tough to get a full zwave-plus network.