If you are not performance driven, it will not make much difference in most cases. production bows are built to withstand extreme draw lengths, and guys with shorter draw lengths do not get the performance that can be obtained with a longer draw. 2" of power stroke makes a big difference on your arrow trajectory.
Having a bow built to perform it's best at your draw length and weight, with the grip shape matched to your exact specifications and shooting style, can, and will improve your shooting skill a lot.
of course a custom bow is a bit more expensive. but a lot of guys out there think it's worth their investment. Kirk