Rob, I've noticed that result also. as you saw in the picture, I already had a slotted cup which was used to trigger the devices. It works quite well actually since it was infrared, No light sources will affect it and they are very reliable. The devices I bought are just a little large but I had made mounts for them easily. As for the circuit to accept them as a trigger, it is easily made.
I'd say if you have a design to accept them, go for it! I am willing to change anything needed to use them.

John