I'm going against the majority here, but I would leave the bumper as is (if the new bumper gap isn't that noticeable). Your damage in the photo appears like a bug splat and (to me) is barely noticeable. As your bumper is in a "danger zone" area (rock chips, parking taps, etc.), I would wait for some more wear and tear before replacing the bumper.
Plus, you never know if the body shop will get the car back in perfect shape. There are often issues with overspray, PDC sensors misaligned, etc. Ask yourself if it's worth the paperwork, loaner car, mechanics playing with your car, etc.