The shaft I just got in is a Mcdermott I-3 shaft. It's roughly equivalent to the Z-2. The other shafts I have are the I-2, which is roughly equivelent to the 314, or the OB1. They run about $200.00 on eBay give or take depending on the joint style.
The only reason I went with the Mcdermott shafts is because I use Mcdermott cues and I like their warranty. Other than that I suspect most of these LD shafts will feel more or less similar one you break them down into their various classes and from there on it becomes a choice of Coke or Pepsi.
I had an opportunity to try out a friends OB1 the other day and it felt very similar to my I-2 shafts. Hard to say for certain though because he is one of those guys that removes the weight bolt from his cue and I really don’t like using it.
From what I can tell the choice comes more down to your playing style more than anything else.
The 12.75's seem to be good all around shafts with medium deflection. They are very comfortable to play with and most people like them. I loan mine out all the time and so far everyone has really liked the feel.
The 11.75's seem better matched to players that don't put a lot of power into their stroke. I would suspect that players with more of a power game would prefer the 12.75mm
Interestingly enough when I first tried the I-3 I loved it, but was playing on a 9' Brunswick GC with Simonis 860 cloth. Last night I tried it on an old bar box with worn out Jim Beam promotional cloth and it was absolutely horrible. Idunno perhaps it was an off night for me but I couldn’t hit a thing with it. I suspect the reason for this is that it might not be well suited to conditions where you have to really hammer the balls to get any cue ball action.
I think I’m going to sneak out after work and try it again on some bar tables that are in a little less of a broken down of a state before I pass judgment.