I have a C 100, which came with two, 15 round mags. I also bought two, 14 rounders, and a 16 rounder. They all fit well, and work great. The 14 rounders are shortest, so I prefer them for CC. It is possible, C 100s were offered with different mags over the years. Similar to the grips, which vary a bit, from year to year.
I have had the C 100 about a month, and fired about 500 rounds. So far, not one hiccup, with any of the mags. I have not owned a CZ75, but do own a CZ82. I like the CZ82, but cannot imagine any CZ being better than the C 100. It is very well made, with excellent fit, finish and function.
I doubt you will be disappointed. If you do not like the mags it comes with, buy some you do like. They are only $25-30 each.
Thank you for your service