I really don't understand people saying you need to be more precise with the Z2 vs. the 314-2. Or any other smaller diameter shaft vs. a more tradtional size. But maybe that's just me...
I played for 15 years with a standard Schon shaft, turned down to about 12.25 or so. When I first tried a predator, after a long layoff (6 years), I gravitated more to the Z2, plus that was the one I got to test hit longer, so I bought that. Played with it for 2+ years, loved it.
For some reason I wanted to try a thicker shaft, so I tried a 314-2 and eventually bought one of those. After some trial and error, I ended up switching to the 314-2 and have been playing with it constantly for the past few months.
I can play the same with either shaft, I certainly don't feel like one requires any more precision than the other. Maybe it's the sight picture of a thinner shaft that gives you the perception that you have to be more precise, but unless someone can scientifically explain to me that it's true I don't believe it, you can still move the contact point on either shaft over .5mm, 1mm, etc. and fine tune english in a very similar manner, one just looks like it's more off center than the other.
Spin is the same - another myth I hear people say - I can shoot every stroke shot with the 314-2 same as with the Z2. Yes, in theory you can get slightly lower on the ball without hitting the table with a smaller shaft, and therefore have slightly more clearance on extreme draw shots, but the difference is so minor it certainly wouldn't be a factor in normal play.
Deflection is less with the Z2 - while I can certainly shoot all center ball shots interchangably, I definitely had to retool my english adjustments for the 314-2 and have to be very conscious of that when switching back and forth. However, I do find the 314-2 to be more "standard" - far more good players seem to play with a shaft in the 12.5 - 13 range as opposed to under 12. And even though the Z2 is stiffer with it's taper, I feel a more solid hit with the 314-2 because of the larger width, just feels more solid.
I may end up switching back again, who knows, they are both good shafts. I think it just comes down to which thickness is closer to what you are used to or what you prefer and which feels better to you. Try both if you can for 30 - 60 minutes before you buy, you'll save yourself having to wonder later on like I did. Hope some of this helps...
Scott