I'm planning to do some negative scanning with a phone or iPad as a light source. I know I'll have to make some simple tweaks to the color balance of the scans. I believe it is totally normal to have to make some adjustments to scans, the side by side example in the article seems to show that a white light source is perfectly fine for this work. It's unlikely that an RGB light source would produce scans that don't require any adjustments, so I'm failing to see the benefit.