Re: Pre-payment for the HAIII black SF-III.
Brass reacts to the sweat of your hands and gets ugly, oxydation I suppose. I think that this process also developps a metallic smell. I have no brass lights or other objects, so you may correct me, if I'm wrong.
Polishing the light surely works to keep it shiny, it looks very nice indeed. I just wonder about aggressive knurling, I don't think you can polish that successfully.
In another thread, they also talked about different materials and got crazy : Carbon fiber, sterling silver, gold, platinum, depleted uranium... :shakehead
I like titanium because you can give it different finishes, it needs no care, feels great on skin contact and doesn't react to anything. I like stainless steel as well, but it's too heavy for big lights, AAA format is OK, I have one AA (Jetbeam Element E3P) which is already quite heavy.