Quick comparison between DJI's neutral density filters and PolarPro's Cinema/Vivid ND + polarizer filters. Exposure settings identical between both filters.
The color shift between the two is very interesting. I'd say the PolarPro is closer to correct, despite being a bit warm + green. The PP had a deeper blue sky on the SW-facing shot, but the NE shot was washed out. I left the titles alone so you could see the difference in exposure.
Camera settings were as follows:
DJI Phantom 4, v. 1.1.411
4k 30fps (slowed to 23.98)
D-Cinelike
White Balance: Daylight
0, 0, 0