p.2 #1 · einstein flash head slipping on D600 boom arm stud
Drop-down pin plus safety cable is the ticket. I use a baby Matthews drop-down on my Avenger D650 (which could also take a massive junior drop-down). Anyway, hanging a 20-lb load upside-down is no problem at all. Profoto fixtures and heads provide all-aspect head adjustment: if yours are lacking that feature, select the swivelling version of drop-down.
The F830 affords a more limited range of motion than the E700 drop down pin. These two photos demonstrate the maximum upward deflection of a boom arm that still permits the baby pin attached to an F830 and E700 to remain perfectly vertical:
F830:
E700:
In the case of the F830, if the boom arm is raised further, the baby pin will deflect: