I just bought the Jem'hadar ground set upgrade from the Lobi store mainly for the Jem'hadar outfit armor visuals. But some uniform pieces still show up and aren't overwritten.
No matter which uniform I am wearing, when I turn on the armor visuals in the character status window, my uniform boots show up instead of the Jem'hadar boots that go with the visuals. Uniform belts show up also as well as my winter scarf. Uniform gloves also appear.