Not exactly sure where this 'face flatness' talk is leading. A lot(putting it mildly) have bought Hireko irons and played them. I'm assuming, played them 'well' or up to their personal level of play. Are the faces flat on my irons? I have no idea, and I have a few different sets from various companies. Would it make a difference if they are not flat? Again, I have no idea. What I do know is the fact that almost all driver faces are not flat, and if they are, can be a hindrance to performance. So, maybe Hireko knows something with the way they do manufacturing.
Am I checking my irons after I post this? Hell no; I got better things to do.😜