Contrary to the thread title, I like nickel silver very much. Taking three base metals (copper, nickel, and zinc) and melting them into a convincing facsimile of sterling silver is pretty neat.
But right now there is no reason a dwarf would ever ever make this alloy. It has a value of 3, which is nice when you consider that the constituent metals are each worth 2, but then you realize you could have just dumped all your nickel bars into a chasm instead and wound up with half as much brass (value of 7), which would still be worth more.
Just to be clear, I'm not complaining about the nickel content diluting the value of brass in the same way that, say, rose gold is worth less than pure gold. In that case the total value of the alloy is the same as the ingredients. I probably wouldn't even mind if the nickel added no value at all, i.e. 2 nickel silver statues being worth the same as 1 brass statue. But the nickel content of nickel silver effectively has a negative value, and that bothers me.
Making nickel silver does produce 4 bars at a time, but even if you had no magma and were dangerously short on fuel, and you didn't even care about material values, you'd still be much better off making brass, since you can smelt brass straight from ore.
Fortunately this is simple to change in the raws. There's several ways to solve this, but my suggestion is to up the value of nickel to 3 and nickel silver to 4, and change its formula from (4 nickel silver = 2 nickel + 1 copper + 1 zinc) to (3 nickel silver = 1 nickel + 1 copper + 1 brass). Aside from this being closer to the makeup of real nickel silver, the output has the same value as the input metals this way, but using brass as a component metal makes the dwarves work that extra step to make it. (If you don't like increasing the value of nickel or nickel silver, you might instead experiment with lowering the value of brass.)
In the meantime until I generate a new world with these raws, I'm planning on making lots of plain nickel barrels and drowning any noble who even thinks the words nickel silver. Wish me luck.