The Breitling Emergency is good fun but last time I looked at it, the transmitter emitted only on 121.50MHz.
This is a low power transmission (which one finds on all other beacons e.g. ELTs and EPIRBs too) intended to facilitate close range VDF, and works only if the rescue vehicle is within something like 10nm and is equipped with VDF.
So, if you simply ditched somewhere, the watch alone probably won't help you. An airliner flying nearby/overhead and listening to 121.50 might just pick it up and report it... One would have to do the whole works to make sure they know pretty well where you are going down.
If they emitted on 406MHz too that would be something else, but they would need a lot more power than they have to play with.