I’m surprised to see most folks don’t see any increase in accuracy over the standard full size Glocks. .
Well most folks is really on a few shooters of GT (Try BrianEnos.com for thousands of Glock shooters). In theory, a longer barrel would produce greater accuracy at longer distance. However, if you were to use the same ammo in each gun, and test each gun in a Ransom rest at 7 and 25 and 50 yards, you would be surprised. The G26 produces a tighter group at close range, and the G17L produces the best group at 50 yards. Now the ammo has to be just right, because 9's are not inherently as accurate as the .45acp. Now attach a shooter to a gun. Say your G17L can hold 2 inches at 50 yards OEM, and say 1 inch with a oversized hand fitted barrel and custom handloads with a finish reamed chamber. If the shooter doesn't have the fundamentals down: stance, grip, sight picture and trigger control, they will be throwing a 10" at 15 yards. Keeping in mind that a Glock trigger can never be a 1911 short rest light trigger. And is a 10" group at 15 yards acceptable for self defense? Of course, if you don't take all day to do it....