Just say no.
I did aluminum nipples once. It's just not worth it. I'm fully convinced that no combination of care, tooling and antisieze will prevent you from rounding them off if you care that your wheel is semi-true and are the least bit un-smooth. It was worse than being married to a ginger. Either one could ruin your day at a moments notice.
The g-sport nipples are most likely tons better, but you're still going to end up galling a few of them eventually to save like two ounces while you're possibly running 27 ounce tires.
If you're already on Kevlar bead tires, some stupid light rims, .8mm thick tubes and titanium spokes, cool. have fun. Otherwise there are less painful ways to save rotational weight.