Greetings all,
Am working with spotlight right now, and had the following ideas come to mind what I think could be useful:
First is - An option for :
Use color channel normally, AND image alpha for zdepth - could paint color and depth at the same time !
Second - An option for:
A mode where grey is 0 displacement, black positive and white negative or vice-versa. currently everything is either pushed or pulled with Spotlight. Combined with option #1 this would make me very happy !
Btw I’m quite new to ZB, please let me know if I’m missing something and something similar is in existence already 
Cheers
S