Sorry for not responding to that one, I’ve completely missed it. 
I never understood the difference between monostable and bistable buttons, even Googling has led me to confusion. Can you please explain in layman’s terms?
Bistable button has two states - pressed and not pressed where it either opens or closes the circuit. The example could be a simple light switch. Monostable buttons close the circuit only for the time they are pressed and as soon as they are released, the circuit is opened. They’re most commonly used for the doorbells - that’s why they are also called doorbell buttons. However, due to the nature of the smart home where the light could be controlled not only through the button, but also through the central gateway, they do not close/open the circuit which leads the power to the light itself, but rather give a short signal to the in-wall module with wireless capability (WiFi, Zigbee, Zwave etc) which manages the actual light power. This leads to a benefit of not having the switches all around the house in random states where some of the lights were switched with the use of a button while another were controlled through the automation or the mobile app.
How much of a big deal is it? I have over 20 shutters in my house so if it’s very time consuming and not very reliable it’s going to be extra problematic for me.
Well, I can imagine it’s at least few minutes spent with each shutter to calibrate it properly once the setting is there. I wouldn’t call it a big deal, since it’s a one time job - unless you like to reset your smart home gateway often and the module forgets the calibration settings after reset. Obviously I didn’t have a possibility to check the latter part. 
I’m now trying out ZHA and liking it much better than Deconz + Phoscon. Any updates in general about this shutter controller, would you recommend it/something else? Also, is it true those only work with the Tuya Zigbee hub?
As you can see from what I posted, it works fine with ZHA - the only thing missing is that calibration functionality, since it’s not implemented in the ZCL-compliant way. Personally I’d prefer such modules to expose only the minimum functionality with Zigbee (eg. open shutters, close shutters, stop opening/closing, set specific percentage) to limit the chance for manufacturer going creative with implementing non-compliant ZCL clusters while the extras are controlled through the physical buttons on the module itself.
The module @FaBRiK linked above looks nice - it’d be good to find the manual for it, check out how the calibration procedure looks like and if it requires using manufacturer’s gateway or rather the buttons on the module itself. In the former case the chance that calibration is implemented in non-compliant way is much higher. If it’s the latter one then I’ll happily pay extra for not having to rely on any custom handlers - it’s still much cheaper than Ubisys and even cheaper than Fibaro.
According to the comments the module works with deCONZ, but has some problems. The person who made that comment didn’t elaborate on it, so I can’t really say what could it be.
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