Interesting idea, but being a fairly successful new straight shaver myself, I say skip the balloon exercise for several reasons.

1. A balloon doesn't have WHISKERS---especially thick, wirey ones.
2. You won't feel the blade and how it's reacting to your face. The balloon won't tell you either!
3. You're probably not going to shave that balloon in the mirror, are you! You aren't going to learn all the contortions you need to do to shave certain areas of your face. Is your face perfectly smooth and round? On the other hand, your face doesn't pop if you nick it, flinging shaving cream everywhere!

Skip all the hooey and just do it. Just make sure you've done a little reading and watching of videos or others and you'll figure it out if you want to. It really is not rocket science or something to be terribly afraid to try. Just remember, EVERY guy used to shave like this--it can't be that hard. With regular practice, I'm convinced anyone who wants to can get a superior shave with a straight. Good Luck.