You need to re-read the quote about the dispersion of the shooter being added to the dispersion of the gun. That's it in a nutshell.
John [/QUOTE
How inaccurate do you think a xd, glock, or m&p is at 25 yards? If those guns were only capable of 8 inch groups at 25 yards, then yes you would have more of a point. Those guns with the right ammo are likely 2 to sub 2 inch guns at 25 yards with tailored ammo.
If you had no control over when to fire, the movement of the shooter would play a significant role over accuracy. However you have a trigger that allows you to fire consistently at the same point (or very close), which helps lessen that effect. You could have a 3 foot arc of movement for POI at 25 yards, and as long as you pull the trigger at the same time each time with the same sight alignment your POI will only be within the guns mechanical accuracy, which is less then anyone on here could shoot off hand.
The OP owns a glock 17 and mine is most certainly capable of sub 3 inch groups at 25 yards because I have shot that a time or two while standing. So the real question is how well can he shoot his glock 17? If he can't shoot 5 inch groups with it at 25 yards upgrading to a high end gun isn't going to make him a 2 inch shooter. If he is shooting sub 3 inch groups at 25 yards with it he could benefit by a upgrade.
I am trying to get the OP to the results he wants, not to spending a lot of money without results. Your average person tends to think a typical handgun is only capable of 3 inch groups at 21 feet. Judging by the OPs level of experiance and familiarization with higher end pistols, I am willing to bet he doesn't realize how accurate the guns he owns are. We might disagree on things but I think the OP could benifit more by paying for training and buying lots of ammo. If he just wants to own a "super accurate gun" for the same of owning one, yes all there is to it is buying one. If he legitimately wants to shoot accurately there is a lot more to it then just buying another gun. That's what I see training people on a weekly basis, is most people think you have to buy a 1,000$ gun to shoot 2 inch groups at 7 yards, let alone 25 yards.