I bought the diffuser. Horribly over priced piece of flimsy plastic that does softer the light. I prefer the look.
I’m a noob so no clue what it actually does for par/whatever, but it does make the lighting less harsh.
I use it and like it - but you know it costs them like $0.10 to make. They should have included it with the light and the add’l $30 or so is just a kick in the nuts.