We don't do many reloads in PCC so I wouldn't make reload times your primary decision factor.
However, since the EndoMag maxes out at 30 rounds, that will cause you to do a reload on a 32 round stage versus other shooters running Glock/Colt mags with a magblock or dedicated lower who won't need to reload.
You have options ... for roughly $200 you can buy 4 EndoMags, or a dedicated Glock or Colt style AR9 lower, or a magblock to use with your current 223 lower.
If the EndoMag works well, maybe we can convince them to make it for 40 round PMAGS.