Those original ones do look quite sizeable. These are the size of the ones I use for multi-circuit switching.
I do still need to update that driver for the different variants, and I'm sure the ones I have are no-neutral. Because I'm definitely using at least two of them. 
Post back when you've decided which way might be best to go - if you do give Zigbee2MQTT a shot and can send me the logs of what's received, I'll try to find some time to modify my Xiaomi driver to support them. 
