I am currently playing your 712 MB irons, and before that I played your 680 MB irons; so you can see I love your clubs, but would like to see future models with a few modifications (or custom options). Since your MB irons are for the lower handicap golfer, I would like to see the swing weight increased to D3 or D4, and the lofts stronger by 2 - 3 degrees. Your current models are fine but I have to add so much lead tape to them in order to feel the head of the club. And if I order them 2 degrees stronger from your custom department, the leading edge and bounce on the club will be altered, causing the leading edge to dig into the turf.
I understand that the lighter the club, the more swing speed you can generate; but the better golfer, who this line is designed for, isn't necessarily looking for more distance, but accuracy and timing which is derived from being able to feel the clubhead throughout the swing. They are also looking for trajectory control, which can be accomplished by making the lofts stronger. cally did this with their X Hot Pro irons and I probably hit them 8 - 10 yards farther than my current irons. I'm not looking to change clubs, I love the classic look of the Titleist MB line; and have hit blades all of my life. Anything else looks quite complicated.
In summary, there are multiple options out there for high handicappers; I just wish that your MB line was truly designed for the low handicap golfer. Give us some options too.
You could add some heavier weights to the weighting system inserts for your 913D driver as well.