well its good to hear a lot of pros and cons about starting the PS with a quote. Here are my thoughts:
First of all, if one wants to use quote; a really good quote is needed. And with a really good quote I mean how it can tell your story within its apostrophes.
Secondly, based on the responses, I think a quote is a risk; but if it works out, it can pay off really well.
Lastly, if a quote by Mr. X is used as the framework of the PS, the applicant must have strong reasons to explain why he chose Mr.X
But, please keep your opinions coming, it will definitely help other PS writers around. Thanks