And I have never used it for that. Never thought about it. Always got the heart piece before the Magic armour.

It's a bonus in the game if nothing more. I use it in the Gerudo Mesa (Cave of Ordeals) in the last room where there are the 3 darknuts. Nothing else rely But it is useful to make room in your wallet because as how I see it the money is an issue in the game. There is too much of it and too little to spend it on. But other than that is one of those get 100% finished game of just don't get it.

I tried it! I just had to. Having 0 rupees with the magic armour on does not constitute for having Iron booths. The Goron elevator wont operate that way and you can't walk past the steam holes at Death Mountain. And you probably won't even sink. The sinking I did not try but I doubt it as it does not work on other places as the iron booths either.