Not much to add to TD's post.

Fender's mostly finish their necks in a natural or tinted/stained finish. Gibson, Gretsch and Rickenbacker tend to finish the neck like the guitar. BC Rich's are uncommon enough that I think you can pretty much do what you want without calling you on it. Most bolt-ons are finished natural-ish, but that's probably because most bolt-ons are copies, or at least variations on a Fender theme.

FWIW, I think the hammered paint look would look great on the headstock, but I don't think I'd use it on the back of the neck. Most people don't finish an ebony or rosewood fingerboard...but Rickenbacker does, and if you like that look you can too ;-)

Talking about that, I am curious whether you'll put a clear coat over the hammered finish? I have been using a satin finish on necks, because I like the feel better than gloss or semigloss. I have been using semigloss on bodies since I learned that it flattens a bit better than semigloss. I also use semigloss now on the top of the headstock. One thing I would recommend to anyone is to do a thumb test with whatever finish you plan to use on the back of the neck. When you run your thumb along the back some finishes (particularly the glossier ones) can feel "sticky." To me, the satin finishes feel less sticky and faster. I actually used to keep a maroon sanding pad around to satin-ize a couple of my glossy necked guitars.