One thing to consider is when it's too much noise or xgen hair is penetrating the base mesh - this can cause artifacts on baking. you are welcome to check my timelapse of the hair cap baking - not the lashes and brows - but the same workflow - maybe it could be helpful. https://youtu.be/_IU4DkEWTwI (sorry for the audio)
Sorry for the thread necromancy. Just tried this out myself and it seems to work beautifully. @Neox - Great trick man, thanks for posting it. Should also work for Zbrush Fibermesh hair if you've remembered to assign UVs to it ( doesn't happen by default). Just a quick sanity check - I assigned the 128, 255, 128 map as a…