There are more factors that matter than a couple inches of barrel. Some people have actually got better accuracy by shortening their Mini's barrel, makes it act stiffer, less whip and vibration. The quality of ammo used, torqueing the gas block correctly, adding a strut, smoothing the trigger would all probably help more than having a couple inch longer barrel.
If you have good eyesight, have the Aimpoint with the 2 MOA dot instead of the fatter ones, and turn the intensity down to where there's no "flare" of the dot, you should be able to shoot almost well up to 100 yards with the Aimpoint as with a scope of modest power. Target was shot on the same snowy day with the Aimpoint mounted, load was a 77 Gr. Sierra Matchking BTHP with 22.7 grains of H-4895 in Brit Radway NATO brass. Beyond 100 yards, having the magnification of a scope would give accuracy gains over the red dot. For shooting 200-300 yards and beyond, or shooting at tiny varmints like prairie dogs, I take off the Aimpoint Patrol Optic and put on the 2.5-8x Scout scope, easy enough to do with the Q.D. mounts. I now have a Tech rear peep back on the Mini, and enjoy shooting it with irons from time to time as well.