It is a useful option that could be utilised. BUT as long as it is not through some crappy African "official" exchange rate that is twenty times worse than the black market rate.

A 4% fee is quite high though.

If this existed I would consider perhaps using a combination of all three options available to me:
- cash;
- travellors cheques;
- credit card.

Plus of course agreeing to transfer the balance if any is left over when I get home.

I do not like using a credit card for hotels etc in crappy third world countries where I have no idea what ER is being charged. People can get real nasty surprises this way when they get home.