Notes On UDEV
As of February 2020, the xorg ports now use UDEV.
From NiclasZeising 20200223:
The UDEV option gives us a couple of things. First off, it is the same interface that linux uses, which means it is much more well tested upstream. The devd backend we have used is only used on FreeBSD. It is also the only way to handle input devices on wayland, and having a unified way to do this is good, because then we can iron out bugs in one place, instead of having multiple ways to handle this. In practice, it gives much better support for trackpads, touchpads and the like. For instance, working two finger scroll, taps and all sorts of "modern" features laptops.
You are of course welcome to keep on using the DEVD interface, the option is still there and you can switch to use it. You have to compile xorg-server yourself though.