Have a shoot both. The 3913 is appreciably shorter, smaller and thinner. The grip is shorter, also. I would handle it to determine if it will be a problem for you. Mine has two magazines; one that sits flush to the magazine well and one that protrudes and allows for a better pinkie rest. I am comfortable with either.
I am a 1911 fan, but like and appreciate the qualities of the 3913. It is definitely easier to conceal. It runs like a champ and has never had a problem of any kind. I will mention that the safety on the 3913 works the opposite of that on the 1911. Up is fire and down is safe. Factor that in your decision, too. Some dislike to operate opposing safeties.