So that I make this completely clear, this is NOT a favorite soap selection. If I had to choose a single soap upon which I was compelled to use all alone on a deserted isle—which on the surface of this predicament makes me wonder whether a good shave would be at the forefront of my survival needs—then I believe I would have to go with a puck of Martin De Candre. Why? The stuff lasts forever. Since I would not be certain how long my dire situation will last, I suppose it best to at least be prepared by having a long-lasting soap. The question arises, however, as to how well does it lather with briny sea water? Would I need a particularly dense boar brush to develop the necessary lather? Could I fashion a decent scuttle from a coconut shell? Would I be better off with a stainless razor than a carbon steel model in this caustic environment? And what blade works best in the tropics? I wonder if Robinson Crusoe struggled with these difficult questions?
As you said, you are not certain how long your dire situation will last, so why take a soap that may not be a favorite? After all, it may be your last few shaves this side of heaven. Do you want to be thinking on what may be your last shave, "Man, I sure wish I would have brought ..." Why not go out with what you consider to be the best?
Okay, if I must be honest, MdC is also my current FAVORITE soap, as well. But Steve, since you have an aversion to 'what's your favorite shave item?' topics, I didn't want to you to feel excluded from participation in this thread by use of the "F" word....
That actually sounds like an interesting idea... I wonder if anybody here would be up for the challenge!?!