I was in a turn fight with a la7 in a c205, on the deck. I was turning left but he was closing. I was working the throttle, but he still was getting dangerously close to a firing solution at 200 yards dead 6 (I even took some hits). So I drop gear, already got flaps out, chop throttle more, and he literally passes outside my wingtip, 5 yards away, and because he's faster he keeps going. At about 50 yards I unload into his buttocks.
Won the fight, got away. That said, it's only rarely useful, and I suppose a rudder stomp would have slowed me down better, but I was trying to keep on the ball because I was slow enough as-is. I didn't want to spin out into the trees.
EDIT: Sorry, forgot to specify: This was just this past week. I might go 100 sorties or more before I drop gear in a fight, and every time but once it's been in an f4u only.