I had both the 17C and the 26C [ with a 5" ported aftermarket barrel ].
Both guns shot about the same in slow fire, but when I did Irritating People Squabbling Constantly with the 26, my scores would go down. Like about 25 % lower. I found it difficult to hold on to that squirmy little butt on the 26 in rapid fire, even with the Scheyrer extended floor plates, or a full size 17 mag.
However, that being said, I am now in the market for a 19 C [ again with the aftermarket ported barrel ]. I figure the 17 is too big, the 26 is too small, so the 19 has to be "just right" ... the porridge at just the right temperature.
The funny thing is .... I shot my way into B class with a Detonics Combat Master in .45. The CM is about the same size as the Glock 26, and in .45, I swear it kicked LESS than a full sized Govt model. The lighter CM slide went faster, but had less inertia == the CM had less muzzle flip and less recoil. Of course, the short sight radius on these type of min guns does detract from long range accuracy ... but the greatly increased speed up close and personal makes up for that. Up to 15 yds, the 26 and the CM would do anything I wanted. And there are those who say 15 yds is all you really need from a pistol anyway??
PS: team Detonics used to come up and shoot the BC matches, and some of those guys never even had sights on their mini guns. And they didn't do all that badly ...
[;{)