...The quality of light compared to my diy versions is better due to the fact I have created a graduated face which eliminates the hotspot from the centre of the flash, whereas my diy versions used a flat face which still showed the hotspot but also reduced light.
If you have time I'd like to know the difference, in stops, between a bare flash head and your diffusers. What I do is set up a test subject (in my case a yellow metallic toy car my son gave me) and set the camera to F11, ISO 100, and whatever the max shutter sync speed is for your camera (1/250 for the Canon 80D) and take a shot at 1x. Then set the flash to manual mode and change the power out until I get close to the correct exposure (but not over). Then add the diffusers and change the power out again until I get close to the correct exposure again. It will kinda give me feel for how efficient my diffusers are. I think the last time I tested mine I was losing about two stops.