Basically the same project file I used for my "in the Light" image post without assets and Atmosphere quality samples set at 64. The graininess of the sunrays I'm getting aren't all that noticeable, but it does exist - on my computer's screen anyway.
So weird that Firefox downloads as ".tgd.txt" if I click "open" but downloads as ".tgd" when downloaded. This was happening on last install of Windows. Just must be how Firefox does this now? Weird...
First thing I'd do is change the fog quality to 1, and then voxel scattering quality (GI Settings -> GI in Clouds) to at least 500.
Additionally you don't have defer atmosphere checked, so MPD is effecting cloud quality severely. Unfortunately this means much longer render times, but for the cloud quality, may be worth it. For it to be truly noisless you'll probably want AA7 or maybe AA6 with custom sampler with lower noise threshold.
Thanks, Jordan - I use MS Edge browser for up and downloads, no problems at all. Maybe Firefox and MS don't like each other... ;) I'll take your suggestions, however when I opened the projects both with and without assets, Defer atmo was checked in both (the full renders only), hence the 3-1/2 hour render, on my old-ish machine, anyway. May be time to upgrade the CPU, only 8 cores...
Hmm that's strange. It wasn't checked when i opened it in frontier.