I have played with Predator and OB shafts(314,314/2,z shaft,OB-1,and OB classic)......in my mind the OB classic is a good long step up from the others.The OB classic has a stiffer hit,better feel,and even a better sound when hittin balls.I truely believe the OB classic has improved my confidence in my equipment as well.
In the end you should try out a few types to see what "feels" the best to you,and by try out I dont think you can evaluate equipment in 15 min. either.Borrow a buddy's shaft or cue and see what you think.
Good luck
Rob