Well... Kinda...
There are 38 Super mags that hold 9 rounds, and some that hold 10, just like the 45 mags that hold 7 or 8. For CDP, the MAX load is 10+1 rounds, to level the playing field for those who have Hi-Cap pistols with 12, 14, 15, or 17 round mags, etc, they must start with 10, if you have a 40, you will only get 9+1.
Yes, it's true, that the mags must be loaded to capacity, but if capacity means that you can only load 9, then you load 9.
The main point of the rule is primarily for instances where a Tac-Reload is required. Mainly, they want a Re-Load to occur from battery, and not slide lock.
Most courses of fie are based on 6 rounds (18 per string max), because of the revolvers, even though we all run different classes, most course designs are done with the lowest common demoninator.
I'd be willing to bet, like the previous poster that you can still fire with a 10 round load, but it could be tight, sometimes, a spring or follower adjustment makes all the difference... Good Luck!
EnjoY!