My surgeon leaves the decision up to his patients whether they want to use protein supplements or not. If you choose to use protein shakes, he wants you to drink no more than two per day during the weight-loss phase and no more than one per day thereafter.
On the other hand, I know there are some centers who require their patients to sign a contract agreeing to use protein supplements for the rest of their lives and other centers who forbid their patients from using protein supplements at all.
I'm very interested to see the outcome of the poll. We have a wide geographic area (international, in fact) here in the 'Hood with a vast array of surgeons and WLS centers represented. I hope everyone will vote so we can get a good sampling.