Its pretty common for the smaller planes like the S1 especially with a metal prop. Don't see it much with the monoplanes because the hh is much easier than in a short coupled plane. Never seen points deducted for powering it back and certainly better than exiting off heading.A quick question Colonel, have you ever done ( or seen) this technique in a IAC competition, and if so, did it change the grade on the hammerhead?
Ive only once seen a botched hh (ie half turn spin out of it) at a contest and i've seen a lot of contest flights. Mostly we get off heading on the exit or bridge it too much.
If i were doing airshows I'd either deliberately bridge the hh or power back once the nose was well on its way down from the pivot as its much safer, at least in my aircraft.