Coming from a ST environment which had over 230 devices, the Zigbee devices had far more issues than Zwave. Why? Well, one reason is the frequency - I think many of our homes are flooded with 2.4 Ghz interference. 900 Mhz signals have greater range. When I was on ST, I eventually had to replace two of my Zigbee contact sensors with Zwave because the Zigbee sensors just kept dropping. Once I put Zwave there, I never saw another issue.
High-end automation isn't relevant to the conversation. I'm not outfitting a 20,000 ft mansion or I'd be inclined to go another route. If someone advertises that their hub works with Zwave, it needs to work - no ifs, ands, or buts. Zwave was solid on my SmartThings hub. From what I recall, it was pretty solid on my C3 hub. It's only the C7 that has these issues. I'm aware it uses a new chipset and there may be growing pains, but it has been on the market long enough that they need to be resolved.
I'm also aware of the advantages to Lutron, but I'm not prepared to make a wholesale switch yet and it's irrelevant to this conversation and thread. This thread is about the constant zwave issues with the C7.