Hi,
it all depends - on the helicopter, the load and the pilot.
Itīs often my daily/nightly job hovering outside ground effect - sometimes from refuelstop to refuelstop - but thats another story.
My boss gives me an appropiate helicopter and normaly I avoid hovering with tailwind.
Doing some freelancing with smaler helicopters, I easily reach the limits of the helicopter - because outside ground effect helicopters need normaly lots of power.
So its really best to reply "unable" to ATC, if youīre not trained or donīt have appropiate power available.