It's hard to imagine that no one who uses the leave in has tried plain aloe vera juice in their hair. It seems like that's one of the first natural ingredients people add to their arsenal. If most people have tried both, yet some people are still using the leave in--I'd guess that the "extra" ingredients are serving some purpose. Ultimately though, the easiest way to figure this one out would be to try it and see what happens
Don't forget to report back!