Rotorque, You ask for comparative examples.
Enstrom 28/280 allegedly gives about 15 seconds grace in these circumstances, before folding up, and will fly at 75% RRPM - and recover
I remember a thread on pprune where an instructor describes closing throttle and counting to ten before lowering the lever in an Enstrom.
Also, allegedly one is able to close the throttle on the ground, lift, do a 180 and land again on the energy in the rotor system. Don't try this in a R22!
I haven't tried any of these and would choose the Robbo technique with the lever if the enqine quits! The extra time allowance should not make one complacent.