I do about a dozen gigs each year filming from a heli w/doors off. Most often the reasons for not using one of our drones is more than 400' agl is needed, a long continuous run is required or there are airspace issues with the drone. It can be a pain at times to fly on or right beside and towered airport for example. It is 100% at ATC's discretion to approve or deny access and some really hate drones. With the heli a radio call is all that's needed. I have a customized Movi for our Dragon that allows me to hand hold it but not support all it's weight. I point it via a controller strapped to my leg. It helps to fly on a calm day and to keep the lens out of the slipstream (having the pilot crab a bit helps with this). Thermals, turbulence and vibration are not your friends in this. The amount of vibration varies a great deal depending on the last time the rotor head received maintenance too.

I hope this helps.