© Taylormade Golf
The M1 driver is available in a 430cc head size, in addition to the more-common 460cc. Most of the drivers on the market today – whether built by Taylormade or another brand – are sized at 460cc's, because that is the maximum size allowed by the Rules of Golf.
A larger club head generally offers more forgiveness on miss-hits, meaning it makes sense for most players to use the largest club possible under the rules of the game. However, that isn't going to be the right choice for every player, so Taylormade has created the option of a slightly smaller head for players who feel that they would benefit from that change.
So who would be a good fit for the 430cc model of the M1? Better players, most likely. The forgiveness offered by the 460cc model may not be as important if you are a player who can consistently strike the ball on or near the center of the clubface. If you feel like you don't need the forgiveness of a larger head, you might like some of the other attributes that the smaller models brings along with it – specifically, the look of a smaller head and a spin rate that will decrease for most players (when compared to the bigger club head).
High spin rates are a problem frequently faced by players with high swing speeds, as large amounts of backspin on driver shots usually leads to shorter overall distance. You want your drives to bore through the air on a relatively flat trajectory, but some players will see the ball balloon up into the air when it is struck with the big, 460cc head. This is a problem that can be counteracted to some degree through proper shaft selection, but you can also help bring your flight down by picking the small of the two M1 head options.
The role of aesthetics should not be overlooked in this equation, either. You need to have confidence in your clubs when you look down at the ball from address, and the look of a large club head sitting behind the ball can be off-putting for some players. This is a matter of personal preference however, so test out both clubs if possible so you can decide which model looks better to you.