I-2
Well I personally own all three shafts from McDermott, the I-1, I-2, and the I-3. I love the I-3, but that is because I like the 11.75mm tip.
All three shafts play really well, and they are all light due to the fact the shaft has a carbon fiber rod up the center of the shaft. I guess carbon fiber is lighter than maple. LOL
Anyway, if you like a 12.75mm shaft, and you like the way McDermott's normal shafts (13mm) play, then you will probably adjust to the I-2 quite nicely. I will put it like this though, if you like a really stiff hitting cue like a schon, or joss or something of that nature it will be a lot harder to adjust.
I have always liked McDermott for the feel, so it was very easy to adjust to this series of shafts. I don't like one thing about them though. I don't like the moori tips.
For years I shot with the regular triangle tips that came with McDermott, and I had no problems with them except that I wore them out quickly. I then went to the sniper tips, and what a difference. I love the sniper tips.
So when I got this shaft I gave the tip a fair try, and trust me when the tip is ready to be replaced it will have a sniper on it. I am sold on the sniper tips.
Another side note. These shafts have a really short ferral on them, and it takes some getting used to that. I have to watch how I chalk the cue in order to not get chaulk all over the wood. LOL Oh well, I love the shaft so it is a small thing to worry about.