diffused light - greenhouses (temp like shelterlogic)

Has anyone here used opaque greenhouses in direct Ontario summer sunlight of the temporary variety like ShelterLogic? Thinking of a 10x10x8 for my 4 plants would appreciate any responses by anyone with experience growing in diffused light polyethylene cover like that (although structure would be in direct sunlight all day).

My understanding is that a structure exposed to direct light all day like that would work fine but not in winter months.

I also read a bunch of stuff online about how diffused light is actually better in some cases than the most direct, top of summer sun and UV (which aparently harms plants?), and how researchers in Holland found better growth from diffused light and how it is becoming the standard in commercial greenhouse fabric? Anyone care to comment?