I also have a rattler (not the H2Yo) but similar... My wife also has one too... We are also not over zealous with the shaking... Generally, we alert each other to something cool that we've found... Small Critter, Large Critter, Shark, etc. It also works for many other situations.
I will also say that since we mostly dive in florida... we have 40-60' viz regularly. So we don't always stay on top of each other, or even at arms length.
Personally I feel these work quite well... Some people find them annoying, and I would too if people over used them. If you ask anyone who has gone diving with us, they generally appreciate us pointing out the good stuff, and thank us for alerting the group.
I will also say that since we mostly dive in florida... we have 40-60' viz regularly. So we don't always stay on top of each other, or even at arms length.
Personally I feel these work quite well... Some people find them annoying, and I would too if people over used them. If you ask anyone who has gone diving with us, they generally appreciate us pointing out the good stuff, and thank us for alerting the group.