Figured I’d report my results. TL;DR: This stuff is really forgiving and worked with any reasonable setting. 800/90/270 was possibly my favorite, but the differences are extremely subtle. The whole experiment is on video: https://youtu.be/Bv1r4M5xCx4
Good post. I was playing around today and decided to try some gold plated key chains that I found at Michaels. This process took less than 2 minutes. There was not any detectable smell or smoke and I am pleased with how it turned out. I used your 1000/90 for the engraving.