Seems like it would be worthwhile to go back to the fitter and try the T300 with the shaft you mentioned. I played several models of AP2's and changed to a combo set of T100s/T200 a couple years ago. Although I am a 6 handicap, my philosophy was that for the times that my iron strike is a bit of a miss, if I had additional technology to minimize the effect of the miss, I may save a couple of strokes per round. For that reason, I scheduled a fitting to try the T300 and the comparison results to the T100s/T200 combo set I had been playing gave better numbers for the T300. I decided to make the change to the T300 and am happy I did so. To me, they feel better than the T200 part of my prior set and although I preferred the look/feel of the T100s, look is not helping me shave a stroke or two due to a miss.

I think it comes down to personal preference. I own the T200's with PX 6.0 shafts. I feel like there's a ton of forgiveness while giving me more of a players look. T300 will look a bit bigger. T200 is "player's distance while the T300 is "player's improvement".

I have played the T300s since they first came out. I like them because they are very forgiving and at my age 76 I can use any assistance. Distance wise guess, we normally get fitted with a 7 iron and that iron I hit around 150 yards, which is above average for my age and I do have pretty good control of it. I had them calibrated in November, because they were two years old and found them to be off and had my fitter set them one degree stronger because I am two years older. Have not played since Dec 12th due to health issues. I should be back to playing by end of April and plan on getting another set of T300s when they come out this fall. I like their forgiveness, ease to hit and accuracy.

The fitter knows best, usually.

Having said that, the Project X LZ is a light shaft.
For a mid handicapper, with a slower swing I would go the T300 to give you that little more forgiveness and meat on the club to carry.
I'm no fitter, i've just tried a lot of the range.

I'm in my mid 50's and I have a slower swing speed. My handicap is about 20-21. I was fitted into the T300's with UST Mamiya Recoil ESX F3 Regular shafts a year ago or so and they have been great. When I strike the ball well, it launches high and long. I know they do not have the slim players look to them, but I still think they look great especially when compared to other irons in the game improvement category. Besides, I am not good enough to really care about looks - I just want clubs that work well for me and help me enjoy the game, which the T300s certainly do. Proud to have a (nearly) full bag of Titleist clubs. My non-Titleist hybrids will be replaced as soon as I can get on my Titleist fitter's schedule, haha.