I've not used them on outboards but if they are the same as the Yammie Jetski's the fobs were water proof and floated. We only used it occasionally but they worked ok. For the jetski's they also had a training mode which was activated through the fob, limiting the RPM, so could be usefull if your training.
I think the fobs had a hole through it so you could attach it to the keys. Then they shouldn't get lost, unless you lose the keys aswell.
That is only if they are the same.