Be afraid - be VERY afraid!
The switch is a funny thing....or should I say switches are several not very funny things?! Because they are a natural material, every switch is individual. They can vary in length and thickness so they each have their own particular character. The switch of a willow tree is known (especially in Ireland) as a 'Sally'. They are generally full of sap so very flexible and can vary from a very thin, very stingy little thing to a much thicker brute more akin to a cane.
I once had an adult school mistress who loved switches. It was one of the most orderly and respectful classes in the adult school! Those things were pure evil. It's like having a cane that creates a line of fire and then leaves behind a stinging liquid that is poured all over your butt.
Personally, I'd stay with the strap.

Your best hope is that your man doesn't think to cut more than one of them at a time because they can split and break if used firmly. That never helped me much because Miss S used to collect them by the dozen and keep them in water just in case. She sometimes went through two or three for a single switching.
Good luck.