I've modified the underexposure zebra point, to my own personal judgement of accepted noise in the shadows.
I've attempted to make this into a menu option, but alas, my coding skills aren't quite there yet.
It would also be handy to have half zebras at user limits, and full zebras at stdev. Like the functionality of zebras in the highlights of dual_iso.
Raw based histograms don't lie, JPG based previews often do.