I've had my TCM apart, it is totally waterproof. I think most Jeep electrics are pretty good. I've also been caught in rainstorms and had water pouring over my instrument cluster. I've rusted out a few blower resistors and that's about it. I've heard some smart people (Blaine) say that the clock spring is vulnerable to water damage. I hope he's just crazy but realistically that's just denial on my part.
Regarding snorkels, if you are looking at somebody else's Jeep and are critical of the snorkel, the hi-lift or just about anything else... you might look into a hobby or something.