Diffusers?

Noob question.

Do diffusers...

1. even out the beam pattern?
2. widen the beam pattern?
3. both?

I would imagine it only evens out the beam pattern since the reflector size and shape sets its beam spill angle.

I ask because Im debating between two flashlights that are otherwise identical but one throws farther and the other has a wider beam pattern. I prefer the floody beam pattern to the throwy one but if I can add a diffuser to the throwy one to achieve the wider beam pattern of the other one then I can have the best of both worlds. Is this good logic?

EDIT: also, dont diffusers reduce beam output?

Both, at least what I can say using my SF beamshapers. I recommend getting any brand beamshaper using a diffuser lens.