I've tried both methods, though in the reverse of that order, and neither have changed the results. Booting into Hekate has worked once, but only after removing all new files/folders first and injecting it via Tegra. Of course, then it can't load Atmos because it doesn't yet exist on the SD card - so not much progress there, but *technically* a change in result.
Update: I can get it to boot into Hekate, and that seems to function mostly SoP (GUI error re: "res file", etc.), but when I try to load fusee.bin from that payload section, it's right back to the double Atmos logos and then black screen as before... Progress?