I would not expect someone who has been using the same tip for over 50 years to change to any other tip, I guess the only way Bob MIGHT change to another tip is if every time he hit the cueball his cue would spit out a $100 bill.....MAYBEThere is defiantly a different sound, more of a ping, I let Bod Jewett, shoot 2 shots with my cue with the green hard tip, I asked him how he liked it, he said "I can't stand the sound"...again to each his own. I believe he said he installs his own elk or tringle tips and has not varied since the 70's
