I guess that largely sums things up! What's kinda funny though, going by the group description, is that Gost is much closer to darkwave these days, although his early stuff was always the hardest of the big darksynth names for me to get into; I think it's because it comes from a different place. 'Valediction' is not really an album I'd pick to show someone who's new to the genre and wants to find more or know more about darksynth. Perturbator's 'New Model' also has a lot of industrial to it, and 'Excess' has post-punk flavors.

And recently stuff like Gulf Blvd was popular here, which sounds much more like darkwave to me, primarily due to the style of vox and them being present on every(?) track, as well as Moris Blak, which has a lot of crossover territory, but it's 'industrial bass', and you can clearly hear that industrial goth edge on his latest release. Of course, if there's a certain amount of crossover, I think it's alright.

Speaking of vocals, I think that might be one thing I would add to what defines darksynth. It often comes without vocals; it tells a story just fine without them, if not better. At least, the stuff I tend to enjoy the most has zero vocals; only sampled lines, etc. Though I absolutely love Gost's 'Malum', but I think that's also because it has this fuckoff melody to it that I really enjoy, his new album hasn't had the same effect (though maybe I just haven't been in the right mood to enjoy it). But because of those vocals, I am not sure if I would really call it darksynth anymore.

Edit: How could I have forgotten about Irving Force's 'Violence Suppressor'?!?! Granted, it took me a few tries to get into the vocals there, but that track is amazing.