AP2 are forged and more foregiving than CB/MB, AP1 are cast. The AP1 has a larger face for more forgiveness than the AP2. AP1 is a game improvement set, by comparison other vendors will also have what is described as super game improvemnt. Being forged, the AP2 has more feel than the AP1. It's hard to say what handicap since the short game impacts that the most. How good is your ball striking? It's worth a fitting to compare your current to either. 15 handicap and up is usually AP1 territory but it is up to you and your ball striking.
A significant number of Titleist ambassodors use AP2 and not just CB/MB, and there are some that do use AP1 at least for their longer irons. So it is what suits your game and your eye.
The other thing is that AP1s are 2* stronger in loft vs the AP2s. Suggestion for sand and gap wedge combo with AP1s is 50 and 54.
I have no need to carry an AP1 6 iron since I carry a 910H 27* hybrid. I have the 7 iron set 2* strong and the 8 iron 1* strong to even the distance gaps; however I do have the 6 available (have it bent 2* weak) in the event I may decide to go to player irons. AP1s are forgiving but still workable and are somewhat less of a GI iron vs an Eye 2.
The big difference to me is the off set and the stronger lofts. I think they both feel about the same, the AP2 is a little softer but not much when you test them with the same shafts. I play the 712 AP1's since it is easier to square up and each club goes about 5 yards farther than the AP2's. I had the 775's before for the same reason. I do recommend a Vokey 50 to fill in the gap to the Vokey 56. My index is 3. Hope this helps
Got the AP2 just recently. Used to be a 1-2, currently about a 6-7. Needed to upgrade my irons and hit both the AP2s and AP1s. The AP2s are more a players club in general. For me the set up more like a blade which I liked. Also they had a lower and more penetrating flight (via the monitor). As for feel, the AP2s were softer, but not a huge difference. I would say if your handicap is 12 or less go with the AP2s. Either way you won't be disappointed. Great sticks.