Just bought a set of Mizuno MX 25
Had three 6 irons made up on with standard S300 DG Shaft, One with RP Project X, One with TT Black Golds.
The day I went to the range there was a 15 MPH headwind. Found the Project X and Black Golds to have a more pentrating and just slightly lower ball flight. All three hit within 10 yards witht he DG being the shortest.
Went with Black Golds because I felt like they gave me more feel.
My local Hotstix licensee freq. matched a set of black golds to obtain my optimum fit. Also had them Pured. I ended up with R shafts but with how they trim them the ended up like a PX 5.5.
Intially without hitting them I went to the coarse and played. I was afraid that I had messed up but after a session at the range I know I made the right decision.