Ray, I recently made the same switch as you and couldn't be happier.  I switched for several reasons from the i15's:

1)  was losing about 10-15 yards of distance per club

2)  was hitting the 8 - gap wedge way too high

3)  did not like the feel of the i15 head even on purely struck shots

4)  did not like the AWT stiff shaft

I was fitted for the AP1's and AP2's and ended up ordering the AP1's with the Nippon NS 105T's in stiff flex.  Some of the immediate changes that I have seen:

1)  distance is back

2)  much more forgiving than the i15

3)  they feel like butter on a decently struck shot

I also tried the DG HL shaft and liked them as well, but very happy with my decision.  Hope this helps.

4)  absolutely love the Nippon shaft

Interesting... I just bought a set of AP1 710 irons to replace my G15 irons. The G15 feels wonderful compared to the i15 and I didn't lose distance, BUT...

To digress... I bought the black dot, (standard), because I wasn't sure I could learn to like them. I was concerned about learning to like a golf club that looked like a surgical device or a farm implement.

I figured black dot would be easier to sell if I didn't like them. Well, I loved them, so I decided to sell them and be fitted for a set of extra long irons because I'm 6'7" tall.

All of a sudden, Ping was telling me they couldn't make a club with a steel shaft at my desired spec in less than a D7 swingweight. I could save a little weight by going to graphite shafts, which I didn't want to do. So, as much as I like the feel of the G15 irons, the almighty fitting program failed me.

At that point, I decided I would look into some slight mods done myself. If I was going to modify a set of irons myself, I was sure as hell going to make a set with a name and look I liked. Welcome back Titleist.

I found a good used set of AP1 710 irons with regular steel shafts, regular flex, D1 swingweight. Using graphite shaft extenders for 1" extra and lightweight grips, I was able to keep the swingweight to D3, a workable feel for my 62 yr old bones.

I'm a really sentimental type. I have to admit part of this is that I simply like seeing Titleists back in my bag.