Just curious if anyone has ever used Rain X or similar type product on and EOtech to keep rain and such off the viewing area. My concern would be that  the alcohol or another chemical in the solution would harm the seal around the glass.  What do you  think ?

ETA : I just got my EOtech recently so it has yet to see any rain/snow I'm sure some of the deployed guys have dealt with this issue, do the EOtechs already have some type of coating or does the weather not really effect it that much?

I've only used mine once while it was starting to rain and it wasn't really a problem using it. I'm not sure if the rain x would hurt the lens or not though.

It doesn't hurt it any that I could tell, but it really doesn't help.

I have only had my EOTech fog up a couple of times, and that has been through lots of deployments in varying weather conditions and lots of range sessions. Rain actually hasn't seemed to bother it. The only notable fogging incident I can recall is one time when we hit an overheated and very humid apartment, after coming in from a lengthy hike in about dry 40 degree air. Even though it fogged up, I could still see the reticle and it worked fairly well as an occluded-eye system. I have significantly more problems with my protective eyewear fogging up, to the extent where I basically consider the "clear eyes" to be expendable for operational stuff.

I do know this... When I checked on using rainx on a motorcycle windshield, I was told it would damage plastic.

I have had enough bad luck with it on a windshield. I would never put it on a precision optic.