I've had a Glock 26, with a ported barrel, and several 17s, including a couple of 17 C's.
After shooting through case of IVI 9 MM BALL [ HOT!] through my 26, I came to the conclusion that the 26, even with the ports, grip extenders, and a mercury filled guide rod, was just too small for lots of shooting ...
in my hands. My practice scores with the 26 were down about 20 % over the same stage with a 17. I'm sure others can do better, but this was what I found. So I sold the 26.
So far the 19 fits best in my hand, balances best, and theoretically, will be the perfect size. It should provide very little loss in practical utility over the 17. If this turns out not to be true, I also have another 5" SS barrel I can port and drop into the 19, and this may be what I end up with as my final answer.
Although I would also but another mercury filled guide rod ...
they DO make a difference in fast double taps.
[;{)
LAZ 1