Just in case anyone was wondering about using a3rd party weigand reader as discussed above, I have an Essex KTP keypad and it works great. I use it to control my garage door so that each user can have their own code, I get vera alerts when certain users open the door, etc.
The only inconvenience is that I have to separately program the user codes for the garage door in the Elk whereas my Yale lock user codes are programmed from Vera.
Other features on the Essex are red & green LEDs that can be controlled from the Elk, keypress output (to turn on a camera or light whenever the pad is accessed).
I chose a weigand KP instead of the Elk arming station so that the Elk data bus would not be exposed outside of a secure area.