I was speaking with a local champion about equipment this week and noticed that he, and many other A level players around here like a skinnier shaft (around 12mm) with a very long taper. I do as well (and I'm NOT an A level player by any stretch...more like a C-). I like my new SW cue, but I'm looking for a used SW shaft that is closer to a 12mm with a pro taper. This player said that he feels he has more control and can get more spin on the ball easier with a shaft like that. He is an A level player, and A+ level money player so his answer is highly qualified. I've played AZ's own, Lou Figeroa (also an A player) a few times and it seems like his Ginacue shafts are on the smaller side and have a nice long taper as well.
I've seen recent discussions on drawing the cue easier and deflection....but I think what is more important is having a shaft the size and taper that you enjoy. Everything else (deflection, etc) is easily figured out with some practice.
What do YOU prefer?