The trace off is this: The 2 extra inches of barrel only get one about 100-150 fps of muzzle velocity, which means about 30-40 yards more range at supersonic velocity at the cost of nearly a half pound. 10-15% more weight for 5% more range under optimal circumstances.
You will never begin in the fight you have planned for. You will begin in the fight the other guy has planned for. Retreat in a manner that leads him into your fight should he press his attack.