The guys from The Ukulele Site have repeatedly stated that with ukes from the same maker and the same type of wood (e.g. Kanilea SF vs Kanilea UV Gloss, Pono AT vs Pono ATD), they felt that the one with a Satin finish had a more open sound whereas the Gloss version had more focus and compression to the tone. Of course, this will depend largely on the type, technique and thickness of the finish that is being used. And as others have mentioned, there are other things coming into play when comparing two ukes of the very same model, like age or density of the specific board of wood, micro adjustments in sanding or bracing, etc.