Yes, loft, lie angles, as well as feel and aesthetics come into play, but this wasn't a DIY combo. I was custom fitted for this set. Discussed at length with the fitter whether better to go with this combo (5i,6i - Mizuno MP 53; 7i, 8i - MP 63; 9i, pw - MP 68), or with 5i,6i, 7i - MP 63 and 8i, 9i, pw - MP 68. The fitter liked the mix of 53s, 63s, and 68s best, based among other things on my 2 hours of Trackman data. Wouldn't suggest that others necessarily mimic my particular set, but (so far) I feel I am getting the very best out of each model's design for my current game.
-- bb