malabo:
If you're simulating engine failures in a 20' hover in a Bell 206, you're setting yourself up for a rude surprise in the event of a real engine failure.
Everyone I've known who's had an engine failure (including me) has been surprised by the failure. This takes away the element of preparedness that you have built in when you're 'training' for engine failures.
Without that element of preparedness, where you will (in all probability) lower the collective after the failure before raising it to cushion the touchdown, the only thing you'll be able to do in a real engine failure is raise the collective.
From 20', having only the ability to raise the collective, you will hurt the airframe and probably your backs significantly.
Start from a low hover, and following simulating the engine failure, only raise the collective. Build up in height until you don't like the resulting rate of descent / impact. You'll stop long before 10', let alone 20'.