Well, thanks for this.

I will not be sailing US waters and contactng USCG is not high on my
priority list. I had thought that the ability to contact a fellow
boater who had only marine SSB may be useful under unusual
circumstances. But I see the error of my ways now.

Let me re-phrase the question -

Is there anything to choose between the FT-857 and the IC-706IIg for
use on a boat on ham bands only ?

How do such sets stand-up to very hot, humid and salty conditions ?

Thanks