I just changed mine to Spectro 6 speed tranny fluid...now for the disclaimer.......I cant smell anything anyway..but wifey has not mentioned it so that is a good sign...oops just realized you folks are referring to the primary...sorry
Oil smells and gear oil smells the worst because of the additive package. I don't think I would base my choice on the smell. Now for the SO that's a different story, smell is important.
I have the smell occasionally, found no leaks, chalked it up to the vent tube. When I had Syn3 in the tranny the smell was oil, now that I have gear oil in the tranny, the smell is gear oil. Doesn't take CSI to figure it out.