Using it in an emergency is scary - you need to be going in an absolute straight line or else you will end up doing a ‘handbrake turn’ which is hard to control unless you’ve had practice. Even going straight, you are likely to end up in a handbrake turn. Using gears to slow down is often more effective - especially the higher the speed. But I guess if you are running out of distance coming up to an intersection it’s all hands to the pump brake.
(Is calling it a ‘break’ a regional thing, too? 
With full apologies - open goal I am congenitally unable to resist.)
