Lutron is an engineering company that specializes in lighting and holds a number of patents. They aim for 300 ms response time and typically get it, although the cloud to cloud integration with SmartThings may add a bit of additional lag. Most Z wave switches aim for 500 ms response time, but maybe closer to a second. With a cloud round-trip it can even be a second and a half. Is that difference noticeable? Not for most people, but some will.
That said, a lot of people prefer the rocker switches, so it just comes down to your own preferences.
Both Z wave and Lutron switches will work fine as physical switches if the SmartThings cloud is not available.
If the SmartThings cloud is not available, but the Internet is working, then the Lutron switches will still work with Amazon Alexa or Google home, which Z wave switches will not. That makes a difference to me because I’m quadriparetic so voice is my primary way of using the switch, but it may not matter much to other people.
The Lutron switches will also work with HomeKit which the Z wave switches will not. Again, ordinarily that wouldn’t matter as long as SmartThings is working. For me again, it’s kind of a “plan C” since if the Internet is down I can still use voice with HomeKit on my smart watch and my Lutron switches would respond.
The Lutron switches do not require a neutral wire at switch box, which is a big advantage if you are in an older home but likely won’t make any difference at all if your home is less than 20 years old.
And the Lutron switches can generally dim lower than some models of zwave switches, but again that won’t matter at all to many people.
So there are a few advantages from an engineering standpoint to the lutron switches, but they might be advantages you’d never even notice. And you could probably find Z wave switches which are a bit less expensive if you wait for sales and shop around.
I would say both are good options, so it’s just what works Best for you.
As far as the Serena shades versus the Z wave shades did advantages are pretty much the same. The Lutron are very slightly peppier, work with HomeKit, and provide voice options even if the Internet is not available. But many people wouldn’t even notice the difference, so again I think you just choose the one you like better.