As Dave McC stated, I sometimes prefer flush-mounted chokes for hunting. I doesn't make a lot of sense to get a shorter barreled gun for grouse hunting only to add an extra inch and weight onto the end of the gun with a big choke tube.
I suppose another example is if someone had a gun that was already too muzzle heavy. They may want to avoid adding any extra ounces at the front end of their gun.
Aside from that, I suspect extended makes the most sense.