Motion Detectors: Infra-Red vs ??

Sure, IR will work if you have the right sensor (or combination of sensors). I don't know anything about the Insteon sensor. Is it even waterproof?

Personally I would use a dedicated panel to handle the automation, that way relay outputs can be customized to any level your imagination will allow. You could use industry standard parts and not have your hands tied to a particular manufacturer. The ELK-M1G is highly touted here from those that tried them. I have not.

How about using the motion to trip a sprinkler? That should scare the deer. Around my area people do the exact opposite -- they trigger feeders and cameras with the motion detector.

Per G. Morgan:

That was my initial plan. One of those jobbies that shoots a stream and ratchets around a radius.

Posted something on misc.rural and, from the replies, it sounds like deer quickly acclimate to almost anything that is thrown at them: noise, lights, water.... There's an initial period when they're frightened by anything unfamiliar, but it soon becomes familiar.

One guy said this sprinklers actually *attracted* dogs and birds.

So I really don't know what the other half of this little venture is going to be..... if anything.

But the detection/trigger part is good enough for now bc I also want selected floodlights to come on when somebody's walking around in the driveway or yard.