I don't really know the answer but I have had some survive a dip at the recommended strength. The problem is, according to Borneman, the recommended strength is too weak to do much.

I do know that acro crabs (the real ones, I call them bandits) can be real touchy little critters. One time we had lost an acro and I wanted to move the acro crab that was still in it to another acro. So I took the dead acro out and carefully coaxed the acro crab into a cup of tank water. By the time I walked over to the tank with the cup, the acro crab had just up and died. It was weird, I never even touched the little guy and it wasn't out of water for more than a minute.