I was doing the safety demo a couple of weeks ago when the tow bar broke causing all us FA's to go flying and I landed in a passenger's lap (very glamourously of course!)
I have no doubt whatsoever in the power of any aircraft's brakes and am always on the alert for naughty mischievous pax when taxi-ing. It's like the kill your speed adverts on the tv - it's there for a reason and if you don't like it then don't fly.