I run an ND filter on my normal camera for three main reasons:
1) I want a shallow depth of field to isolate my subject from the background but it's too bright to shoot wide open.
2) I want to keep my shutter speed at 1/60th sec so motion blur looks natural.
3) A shutter speed of 1/60th forces me to stop down to f/22 or higher causing a decrease in sharpness due to refraction.
None of these really apply to drones. It's no big deal to bump up the shutter speeds on normal drone footage.
Typhoon H uses the same camera as the Q500 4K, the CGO3, so it will use the same clip-in filters. I took my filter out after noticing some nasty lens flares. I would gladly pay decent money for a coated, glass filter for the CGO3. Someone needs to make one...
Overall I've been extremely happy with the quality of footage I've gotten out the the CGO3. In bright daylight it's right up there with with my Panasonic GX8 4K camera.