This is the thing people dont seem to understand when saying that it was only tested when the filter is submerged...

Thats because thats the only time hydrolock occurs. If your filter is properly cleaned/oiled, than you dont have to worry about splashes of water....it just gets vaporized. Submersion is what you have to worry about, and with the BPV, submersion becomes no concern in terms of safety...so it does its job in preventing hydrolock.

In terms of losses...look at its design. Theres no way that valve causes major losses from an intake that only has a few whp to spare anyway!?!