Ive been wrestling a bit with this issue lately. A number of things ive been trying to engrave have either been burning or just obliterating completely on the lower power and highest speed. (paper, cork, foam, cedar)
e.g.
Keep in mind these are raster engraves. I havent been trying vector scores, but this fix could apply to that as well. I have found a hacky way to get a little better results for these sensitive materials. my images have all been grayscale images with black (0,0,0) being the darkest color. If you take one of these files and scale the output levels to make the lowest output level/color a lighter shade of grey like 50% (128,128,128) grey and up, it will effectively still reduce laser output power even if power is set at 1%.
so the image above ended up looking like this after scaling the darkest shade in the file to 50%:
Im assuming you can continue doing this up pretty far to maybe even get close to 1% of 1% of power, but I havent tested that far. Laser tubes have a minimum power necessary to activate, so it might cut off at a higher point unless they accounted for this in the software already. Ive got some other materials I want to test on (paper, EVA foam) and can post results when I get them.