You know, just ONCE I would like someone to ask about tips and indicate what game they might be playing. The kind of game you are playing and your skill level will alter the kind of tip that is potimal for your stick and your game. The thought that one kind of tip is optimal for ALL games ALL tables or ALL cloth is (ahem) not rational.
For example: Games where power is key (say 9-ball) will want a tip on the harder end of the scale, while games where delicasy and precision are key (say 14.1) will want a tip on the softer end of the scale. Players with a well developed deliberate stroke can get along with a harder tip than players with less deliberate strokes. Tables with slow fuzzy felt require slightly harder tips than tables with fast as heck billiard cloth.
I have a friend that plays with a hard tip in 8-ball, but changes to a medium tip for 1-15 (a varriant of 8-ball where the 1 and the 15 are assigned specific side pockets). The added strategy imposed on the 1 and 15 balls, alters the strategy and dynamics of the game enough that tip hardness comes into play. He amanges this with two identical shafts (excepting the different tips).