I do both. On my 3rd gen duty gun - I use it as a decocker - safety off in the holster. My 4566 is equipped with decock only - my 645 and 4506-1 are standard configuration. They are carried safety off in the holster.

In fact, my G&G thumb break holsters can't be snapped shut if the safety is on.

My off duty guns are usually carried IWB. My 3913 being my most carried pistol. I am ingrained in sweeping off the safety on the draw. I still do it, even though the decock only guns have already done it themselves.

I prefer the safety on an IWB carry gun. My 0.02 Regards 18DAI.