Quote from PhanxHave you tried changing the color? The bright green is not hard-coded in; you can change it the same way you can change the color of any other status:
Status > Incoming heals > Color
Considering I am using class color for the health bar, I would prefer to have that text as classcolor+shadow, the exact way the name is on the frame. Only thing I can think of atm, is maybe add an alpha for that text? Maybe if I make it a light gray and put it's alpha to 50% would be slightly visible, won't make me be less fast on the heals, but it will be there to see it if needed. Or maybe add a filter to see that text for Blizz main tanks only?