Clint: I think these guns are all much more accurate then we are, lol. But I guess if you would shoot it from a bench, the MP5 would be "slightly" more accurate at distance.
But with standart ball ammo, you should be able to constantly hit a target at 100-150 meters, with an Aimpoint or EOTech mounted, that is sighted in for 50 yards, if you also know your hold over.
But that's actually phenomenal for a PDW like the MP9, because it was made for the 25 meter mark.