Increased cyclic rate only affects full auto reliability.
Increased throw of BCG is not a problem when a properly matched buffer is used.
Increased wear, but not a major factor if it increases usefulness for specific weapon. Don’t go short unless it enhances mission.
The port pressures at the instant of bullet exit (uncorking) is only a factor if using a sound suppressor. If a sound suppressor is used care should taken to ensure proper one is selected, this should be based on full disclosure of intended platform use before purchase.
I would not ever go shorter than a 10″ barrel.
Mission specifics dictate weapon use, there are valid reasons for a 10″ barrel, just as there are for up to a 20″ barrel.