I have played around a wee bit with the colours because this is really bothering me, and I am really keen on having auto-trading off as a safe-guard.
Although grey is the natural choice for inactive, it does not matter what background colour you choose, you will never get a good contrast. For me the result is that I don't spot the prices changes as quickly as I would with a black foreground.
I have lightened the background colours a bit to improve the situation, see attached screenshot.
We all have certain associations with the background colours (back/lay; up, down). Although, like you, I would ordinarily prefer a neutral text colour, I would probably resort to black and blue foreground colours to sort the contrast issue if I could choose the active and inactive foreground colours.