Lofts in the Forged are "Traditional" and HM are "Modern". "Strong" is another -2dg. Gapping should be done dynamically, so hard to say which suits you on paper without data. In the end it is about distance gaps & trajectories, not loft itself.That being said, 5dg between 8-9 and 3dg between 9-PW while 6-7-8 are 4dg apart seems off. The 5dg gap between HM5 and Forged6 even more so when looking at 'only' 3dg between 4-5. Most likely you'd end up with the 9 being to close to the PW and the 5 too far from the 6 and too close to the 4. The 'fitter' seems to have forgotten the PFS software doesn't change the wedge lofts and shrinks the gap in the longer irons regardless whether it is a mixed set. That's why a program can't fit. Be sure to hit hit both models side by side WITH KNOWN LOFTS and take flight difference into account when making the split.