Long-ish post, but I've been through this and maybe some of this will help out...
I've tried a few shafts over the years, looking for the perfect fit. Played with standard Schon shafts for 15 years - ton of deflection - before I really knew anything about LD shafts, backhand english, etc. Took 7 years off, when I started playing again a few years ago I jumped to a Z2.
After 2 years of that, and another year off due to work, I felt like I was missing something, felt that more good players were using something in the 12.5 -12.75 range, so I tried a 314-2. Couldn't quite get used to it, went back and forth. After 6 months, I decided to "force" myself to switch, so I put the Z2 in a closet and worked on stuff I was having issues with in the 314-2. There were certain shots I was stubbornly trying to make work with the 314-2 the way I did with the Z2, and it just didn't work. Now I use that style of shaft and wouldn't switch back.
Pros and cons - the Z2 / OB2 / OB Pro shafts are similar, and all have less deflection than the 314-2 / OB1 / OB Classic type shafts. Not a ton less, but it is noticeable for sure. Once of the biggest things I had to get used to is that with the smaller shafts, very little if any compensation is needed when hitting the ball at soft to medium speeds and close distances, while a little more is needed for the larger shafts. Once you add distance and/or speed, both shafts deflect, and compensations are needed with either. If you use a method for compensating, like backhand english or front hand english, the pivot points are different enough where your method may need to be changed or tweaked. That's where if you are used to something, switching may cause from issues, at least at first. Now if you stay at or near center ball, both shafts perform pretty similarly.
Personally, I like the feel of the larger shafts - actually, 12.3 - 12.5 is perfect for me, so I either use the 12.75 now or have it taken down slightly. The thinner shafts can feel a little toothpick-ish to me, and can sometimes feel like you are having to pinpoint your spot a little more. Some people don't like the stiffer more conical taper (I don't mind). Don't let anyone tell you that you can do certain things with one vs. the other - neither is more or less accurate, center ball is still center ball, maximum spin is still maximum spin. I can execute all spin, stroke, etc. shots with either shaft the same.
Visually because the tip is smaller, people think you have to be more accurate with the Z2 type shafts, or you can get more spin. While you can technically get an extra mm or so closer to the edge of the ball with a smaller shaft, the miscue limit on the CB remains the same. I find that again visually people sometimes feel more comfortable using the smaller shafts for maximum spin since the side of the tip, which is actually making contact with the CB, is closer to the center of the tip.
All that being said, I can run racks with either, and typically have my old OB2 shaft handy in my bag as a backup for now, until I can get a second shaft of the one I'm playing with. I just ordered a OB Classic to replace my failing 314-2, if I like the feel and performance will probably just stick with that and eventually order another one. It's really personal preference, though. I learned not to try and conform to something because someone else is doing it, or some marketing hype says something, etc. Just like with tennis, golf, etc., find something you like that feels good and performs well, learn to use it and stick with it. It's the archer, not the arrow...
Scott
