@Taco2Cruiser makes a good point. The most vulnerable historically was the rear diff, since the breather was screwed directly into the rear diff. In the 200-series there's a tube that extends it up to the frame.
FWIW I added a snorkel because it was a cheap insurance policy against me doing something stupid. If I'm in >27" of water I probably screwed up. For $250, at least I can be reasonably sure I won't immediately hydrolock. Also it looks cool. I will extend the breathers for the same reason - for $50 (or less) in parts and 1-2 hours I can rest slightly more assured that my stupidity won't cost me.
If you're still worried, the answer is to extend all of them as high as you can. Then you can worry about the electronics next. And the air induction pumps. And stopping water infiltration into your cabin...
