I ended up making an actual video about the technique, which you can watch and comment on here ! I did very painstaking captions, in case I'm difficult to understand. Some additional information:
I was able to process fiber on it at a similar speed to on real hand combs, with extremely similar results--both the palm comb and hand combs produced a good worsted yarn with minimal halo.
I tested 5 different breeds with varying crimp, staple length, micron count, and amount of vm, and found that it performed best with the Ouessant I tested, which is a medium wool on the fine side of average with not a ton of crimp, and neither excess lanolin nor vm--in that case it outperformed the hand cards. But with anything other than very short, very fine fibers (1 inch/2.5 cm long Cormo) the yarns I spun from the resulting preparations were almost indistinguishable.
left: hand combed, right: palm combed (everything below the yellow stripe on this one was picked open by hand as an additional comparison, which was much slower, more painstaking, and nowhere near as neat of a prep)
left image: all 3 sample yarns before blocking--hand combed on left, palm combed center, picked on right.
right image: side profile of swatches--the picked has some fuzz/a visible halo, the other two don't have much.
You can find more details in my original post.