It would have to seriously injest a lot of water for something to happen tho. Doens't really matter much to me either way I dont drive my car in the rain anyway, I have the Jetta for that.
Besides a TSB is when it happens to a very limited number of cars and they either don't know the problem, or are guessing what it is. The chances still remain that nothing will ever happen regardless. Your intake system sucks up water and water vapor everytime you drive in the rain. Most intake systems draw from behind the headlight of a FWD Front engine car, they are just as prone to suck up water, but it just doens't seem to happen or matter.
The chances of that happening with an open air filter that has 360* to draw from would be minimized in my opinion vs. a flat panel filter with less surface area. Either way I just don't see it happening or causing a problem even if it does.
http://www.sportcompactcarweb.com/tech/0104scc_aem_air_bypass_valve/
Here is an interesting article where AEM ran an NSX on the dyno with the filter submerged and only using their air bypass valve. If your so worried about water it really is the answer. Even after lifting the filter out of the water, air bypassed the water through the main filter and never reached the engine. Of course the intake is not how it would normally be, but you can see that even with 250whp it can't draw air up a foot of pipe into the engine, and it's right there.