IMHO 15 rounds in production wouldn't make much difference. It might make a difference if you have multiple positions with few shots, but in the average match where each shooting position has close to eight shots it won't make much difference. If you can't reload your gun between ports in production you are not going to compete. Many, perhaps most, shooters agree that reloading at slide lock can be a bad thing. To take full advantage of 15+1 you would have to reload at slide lock. If you need seven make-up shots you are not going to compete. Good production shooters would dump on the ground a magazine with six or seven rounds instead of a magazine with one or two rounds in it.