mjs10: Most saxophones differ in sound, even among similar models, meaning that you could take three so-called Elimonas and hear/feel differences. Not better or worse, in most cases, just differences.
However, I seriously doubt that adding a pearl touch to a plain S-6 would make any difference. if there WAS a difference, it would probably come from the natural differences among saxophones and not because of some added filagree or peral-whatevers.
Are there differences between an S-6 and a new S991/901/902/992, etc., etc.? Yes - same as the first paragraph, but it is up to the player to decide whether or not those differences amount to anything significant.
I have an S992 and an SC902 - and I'm expecting an S901 this week (from Witchitaband off of eBay). There are differences, but not better or worse. When I play my 1928 straight TT and then pick up my S992 or Antigua 590, they all sound like me on soprano. Different? Yes, but that's all. DAVE