You noted that they are "special" alloy nipples. Do they actually have a unique, proprietary shape that will keep you from replacing them with nipples from other manufacturers?
I suspect that the nipples and spokes might have also been provided by DT, being thst they are from Switzerland too. Maybe you might check with them.
I always avoided the temptation of using aluminum alloy nipples on my wheelsets as they are not as reliable as brass nipplds, and tend to corrode, gall and seize easily at the threads.