Any coupler will work fine if you pay attention to its loading. If you use one of the standard 3D printer couplers you are putting a spring into the z axis system and introducing a great amount of backlash/slop. I have designed it so you can minimize this with the 2 piece mount. That being said my printed one is also a good place to be able to make z axis adjustments. It is a coupler and knob all in one.
The other reason I did it is in the US the 5mmto 8mm standard couplers don’t fit a 5/16 rod very well, and a printed one is cheaper.