Have made use of 'collective braking' in 204s, 205s and 206/Ls throughout my entire career and have had the collective at around 80% pitch just moments after shut down.
Never troubled myself with t/r application (too little benefit) but collective braking can reduce the wind-down time when necessary.
If you leave the lever up too long you will definately start slamming the stops and if that is left unchecked you can unseat the entire transmission. However, long before this ever occurs you can feel it approaching and its simply matter of smartly lowering the collective.
That's what I've done but - I'm not recommending it for others and increasingly new ships have rotorbrakes making this practice unnecessary.