i myself do not have one but i have read that they do work... SCC did an article on it when they first came out and they custom made an intake for this test...
1) Really Nice NSX
2) fish tank full of water
3) Custom AEM intake w/ bypass valve w/ a clear section to see level of water
the intake was made one made for the NSX with a clear part so they could see the level of water when dunked in the fish tank...
and the bypass valve did work... although the pictures they show are scary... i mean you can see the water going up the tube when the filter was totally in the water...
however i have heard that there is a slight loss in power but i would take that over hydrolock, and there was a recall on the some of the bypass valves because the plastic peices would break off and get sucked into your intake maniford (Very very bad)... but to my knowledge this has been fixed
I personally would buy one just for insurance, and still drive carefully shouldn't be going fast in the rain or attempting to drive through huge puddles anyways (had a friend who did that and she lost control and totalled her car)...
idonno if this helps or even makes sense but hey, i hope that you can understand and find it useful