I see a lot of people talking about "performance shafts/cues". What is that exactly? Now the same people are talking about cues like lower deflection is all that matters. It isn't. If you have a super low deflection cue and a normal length bridge, you are going to miss more long straight in shots than you would with a cue with slightly higher deflection. Simply because any mishit will not be compensated by the deflection. The lowest deflection shafts have their pivot points way behind where most people bridge their shots. So actually, for lower level players, such a shaft would decrease their performance on a large number of common shots. If you can't make a long straight in, your pool life will be miserable.
But really, once you get past run-out levels of play, the most important aspect is speed control. It is what separates between players at the highest level. I really mean it, any knucklehead can hit a low outside shot, it's not the challenge in this game. A good player will get out of line because of speed, much more often than he'll miss a ball because of deflection. And even then, I haven't seen any evidence that ld shafts make you miss less.
The challenge is landing on the correct spot, not just tracking the line. A stiff, dead shaft will give you little feedback on your stroke. Every shot will feel like almost a partial miscue. This goes especially for Revo shafts. If I had to choose between a Revo and a Z shaft, I'd pick the latter every time. At least that shaft feels like I'm stroking the cueball and not poking it all the time.