This question is kind of like asking if you fill your gas tank all the way up, or do you always like to leave it a few gallons short just for the heck of it.
The gun is loaded so you have to manipulate it anyway to unload before dry firing. The only downside is you have to deal with the Barney bullet. Since my clothing all has pockets, I haven't seen that as much of an issue.
The only reason I see to not go +1 is due to owning a gun that is unreliable in some way when fully loaded, or if the magazine is essentially impossible to seat when fully loaded. Other than that, I see no real persuasive argument against it, but it doesn't bother me when other people do it.
