Yeah, the stopped-part-way scenario (intentional or more important to me, unintentional) is the main reason I went with 2 dumb reed sensors (1 for full-open, 1 for full-closed)...
I wanted to always be able to validate that one or the other of those sensors was closed (outside of intended movement of course) - that then confirms for me that the door is for certain in its intended position.
The Zen 17 works great because I can tie in those two reed sensors separate from the (opener) relay itself -- that isn't possible with the Zen16. In reality, the Zen 17 really just gives me the advantage of managing the sensors and the opener relay from a single device (so just one thing to power out there vs several things!).. ButI don't use the Zen17 itself to no-kidding "integrate" or marry up the sensors to the relay. Hopefully that makes sense?
I used these reed sensors, but any decent-looking ones should be fine. I wired everything with 18-2 t-state wire because I happened to have some extra, but basic bell wire would be fine too.
To make the 2 reed sensors work with a GDO app (I use Zooz's myself), I thought about getting creative with making a virtual contact sensor, but I just decided to use the fully-closed sensor as the position indicator for the app - works fine for that purpose. I then have rules for stuff like "if one sensor opens, wait ~15" to verify the other one closes - if not, alert me".
And because those sensors aren't directly integrated to / dependent on the relay, I get those kind of position-related alerts no matter how the door is opened (z-wave, wall switch, or dum car remote)
For my dashboard, I have the Zooz GDO app "button" for remote operation, but I also have a tile for each reed sensor -- if both are red (open) ~15" after opener action, I know I got a problem!
I realize one way to solve my door-position paranoia would be to install a camera, but this is out in my detached garage where wifi is super spotty, and I just don't have any interest in adding an add'l wifi beacon out there just for that.
This setup has been great now for the few month I've had it up & running. I think (hope!) the dumb reed sensors will additionally be a more durable sensor solution since my detached garage sees a wide swing of crazy weather conditions up here in MN!