The Silvergarde S cable variants work exceeding well with the He1000se, but so does the Draug V3, with the latter being slightly warmer, and of course, less expensive. I typically prefer listening to the HeKSEs with the Silvergardes for the flavor they bring to the music, but I could also easily use the Draug V3 for the same purpose without feeling that I'm missing anything...They produce slightly different experiences, but deciding which of the two is "objectively better" is not a straightforward matter, because we're dealing with high quality performances in each case. In short I do not see any noticeable compromises with either choice. The Silvergarde S-3, the S3-C, or the Draug 3, will all do a far better job handling the HeKSE than stock cable. As to whether one should go "silver" or "copper," I will have to leave that to personal preference, or budgetary convenience (if budget is an important deciding factor). If you have the opportunity to audition both types with the HekSE in your own system (to evaluate system synergies) before buying, that would be the best option, as it will enable you to nail down with precision what suits you best.
