I don't believe (for most of us anyway) we need to look any further than the loft. I hit my 7-iron better than the 5-iron because there's more loft, and subsequently less side-spin.
I've gone though the the hassles of having my shafts spined... in all honesty - it hasn't made my shots from 175 yards (5-iron range) any more predictable or consistent. Now I could be the rare exception, granted. But as someone who plays 3+ x per week, considers himself a reasonably good ball-striker, plays to a 3 handicap or less during the middle of a golf season - the angle of attack, the ability to strike the ball cleanly, and the ability to continue the acceleration of the swing through the hitting area will always play the biggest role in hitting (or coming closest to hitting) my intended target.
The science only helps if it's a repeatable golf swing and the mechanics of a reasonably good golf swing are being delivered. For a majority of us - that's a huge IF.
Proper shaft flex and swing weight, imo, matters most. It ultimately comes down to making a consistent swing, something that very few of us (myself included) can produce on a fairly consistent basis. If you don't have that, everything else really doesn't matter that much.