I will say this, your endurance will suffer to a degree after about 400-500 rounds in a row if you have to pump each and every time, especially if you shoot full dram 12ga loads. Been there, done that. I can shoot a pump as fast as an auto in most cases, but for comfort in the 12ga, give me a good gas gun like a Beretta or a Remington, (or a Win SX2) and still be on targets at the end of a run.
If you have a proven gun, either pump or an auto, there will only be user preference, until fatigue sets in, then the least punishing of the two will be the winner.