I have used the opto device as a test to replace the hall effect and it is very reliable. The devices I use have 5 leads..the led side has 2 connections, one of which I couple to the other side for power of the reciever. the 3rd line on the reciever side can be eliminated which is the base for the transistor...essentially giving you 3 leads.. power ground and signal, just like the hall.... only faster.

John