I can't comment in-depth on this subject, but many people advocate eating a balanced EFA ratio. Hemp oil is supposed to have a pretty good EFA ratio, but if you eat flax oil and other EFA sources(e.g walnuts) then I do not know if going out on a stretch to eat EFA's from hemp will make a difference.
I think that a lot of the disease in western countries is blamed on bad EFA ratio's. Western diets tend to have only a tad bit of omega 3's compared to a relatively high amount of omega 6's. Eating omega 6's without any omega 3's might cause health problems. I don't think that this means to avoid omega 6's, especially if you regularly eat omega 3's (like most of the people on this board do, I suppose).
Another thing, I don't have any references to verify any of this, I just have read or heard it hear and there--I think it has to do with the pro imflammatory effects of omega 6's without omega 3's.