Pretty much what everyone else is saying too, do you need it to be polished? In what context was he saying to polish it: either you are not getting great reaction with the ball (dry lanes maybe) or is he just giving you a suggestion just based off of what he or others have experienced with the ball?
Also, if you only want one ball and the Marvel isn't getting it done for you then maybe a surface change is in order depending on what you need (duller or shinier). If you want to have an arsenal and have the finances, then getting the pearl isn't a bad idea either.
I would say throw the ball and see for yourself whether you like it or not. If you like it, stick with it. If you want a pearl to go with it, go ahead and get a pearl.