[smellsfishy]

there are likely just covering there but, I doubt they even know what salt creep is.
The way they (the ones i have at least) work is a small hole in the water stream allows water into a blater which fillsup, preasurizing it, which then closes the opening that allows the main water stream through. This is where the preasure comes in, if there is not enough preasure to fill the blater then it will not stop the water. they are originally designed for use on your house water supply wich is always preasurized.
When you want the water to flow the seliniod (power on engages seliniod shaft up against the spring preasure) releases the spring engaged shaft/stopper which is plugging the hole on the other end of the blatter thus allowing water to flow out of the blater which then allows the main water flow to push the blatter out of the way and flow through freely. It takes about 2 seconds to drain the blatter and 2 more to fill. In the valves i use the "in" hole of the blatter is smaller than the out/release hole so it hardly ever gets plugged.
Note if the "in" hole gets plugged which is probably what rain bird is worried about, the valve will just stay open because the blatter will never fill. If it did this on your watering system the water would never shut of obviously bad for an irrigation system.
I actually believe that these valves are better designed for our application than irrigation, then again i'm biased.