If you plan to buy a new Shield in MA, be sure to work the Apex Duty Carry Kit into your budget. It will improve the trigger immensely. My 9mm Shield handles very well and is accurate out to any reasonable self-defense distance (save for snipers of course). I always carry with the 7-rd magazine in the gun, and sometimes put the 8-rd in my cargo pocket for extra capacity.
I usually carry it in a Galco King-Tuk but occasionally use a Nate Squared tuckable when it's really hot, or a DeSantis Insider for deep concealment.
I'm a pretty small guy and the Shield is the largest semi-auto I can convincingly conceal without wearing excessively baggy clothing. The thinness of the frame really makes a difference, especially when carrying IWB.