I don't know if the finish makes any difference in tone, but I am not a fan of the "guitar-under-glass" or that "encased in plastic" look. And that is not to say that I don't care for a poly finish that is done well. If you want your bass to look "nice" years down the road, and you actually play it, then go with Poly. I don't mind a road worn look, which Nitro gives you thru natural and regular use... Don't think I would buy a road worn model though. But I also like my jeans to be blue and without whiskers and "vintage wash". I'll wear that **** in myself.