Not trying to thread jack here, but I am also wondering sort of the same thing. I am a 1 handicap with a 109 average mph ss. I am looking at getting a 660TR, ZCOM MW64, Diamana, AD M65, or Axiv. Should I go stiff tipped or X untipped? How much to tip? The cutoff for most of these is 105 for stiff... Thanks in advance guys!