Part of what makes it possible to build good wheels is working with good components. When we started, we used alloy nipples on the spokes in front wheels and on the non-drive side of rears, with brass on the drive side. At the time, we used silver nipples, as this was before the full blossom of "what have you got that looks like black, but is even more black?" craze.
As we switched to black spokes and nipples, we began to really really hate brass nipples. Since you don't anodize brass, the black color is created by an oxide coating. This has a tendency to clog the threads, which is a real pain in the butt. Since we were using CX Rays nearly exlusively, it was a manageable pain in the butt, since it's easy to hold the spoke and still get high resolution with imperfect threads. Even then, it was enough for us to test alloys for drive side use, and we found that they did quite well. Perfectly, even, so long as you sized the spokes precisely, and were diligent about treating the threads and rim/nipple interface. We've done crash replacements on three year old wheels that live in humid and salty environments (Florida, I'm looking at you), where the nipples spun as if brand new. I don't know how many tens of thousands of alloy nipples we've used, but I know of one that failed. Out of something like 100,000. Pretty good. We did a bunch of corrosion tests last year that showed properly handled alloy nipples are just great citizens.
And then something happened. We started noticing that "tick tick tick" sound and feel during builds. Thread on a new nipple, chase the spoke threads, curse a few times, and get back to it. Eventually, the swear jar was overflowing, serious time was being wasted, and since we now do more builds with Lasers than CX Rays, and Lasers aren't so easy to hold, this was something we needed to address. I'm pretty adept at troubleshooting things, so we set up a series of good tests to eliminate all the variables and what we came up with was... frustration. Black Sapim spokes didn't play nice with any black nipples. Factory threads, Hozan-chased threads, and even now we've tried it with our Phil Wood machine which rolls PERFECT threads. What the f happened?? And then...
We bought some Wheelsmith black brass nipples, because who knows, right? Unlike other black nipples available, the Wheelsmith ones are plated, not painted. This does a few things. First, holy mama them threads are CLEAN. Second, the finish on them is incredibly regular and consistent. Third, they look really really cool. Between bleached black Rail logos and Nimbus Ti hub color, we're obviously fans of the grey scale. These nipples are an exact match for bleached black. It's hard to talk about something as pedestrian as spoke nipples in such terms, but they look elegant and captivating. And they work brilliantly.
The weight difference between alloy and brass was never a big thing for us, although everyone assumed it was. We're not weight weenies, have never been. These weigh about 35g/set more than alloys.
So now we use these nipples.