I think that in a sense, a good argument can be made that it is somewhat irresponsible not to have an extended safety on one's 870.
Once you perceive a threat and you've made the decision to fire, your goal is the deliver that shot as quickly as you can. I don't think there is much universal diagreement that a domed safety is quicker to disengage although people are plenty quich with a Wilson or standard one.
"Of every 100 men that go to battle 70 should not even be there, 20 are nothing but targets, 9 are true soldiers, and we are lucky to have them for they the battle make but ONE, one is a warrior, and HE will bring the others home." Hericlitus