We conduct a good amount of training from commercial, to LE, to Mil dudes, and it's not the color itself but the filmless technology of the WPT that will will give you approx. 20% better performance in extremely dark conditions over their thin filmed counterparts.

The debate rages on if the color itself assists over this and that. Most of the Mil dudes who spend hours upon hours each night say the White Phos. is more relaxing on their eyes. There is supposed to be some new Army Lab report floating around saying the same thing more or less about the effect WPT over green.  For me personally I do not see in the shadows better (except extremely in dark environments I mentioned), but others say yes with better contrast as well.  

P.S. Yes over the last year we've been getting higher and higher on our contract Omni 8 filmless WPT  full Mil Spec tubes reaching close to 40 S/N!  The last one we saw here on the EE I think was 39.7.  With those specs reaching these numbers, we do see some low light performance increases over S/N 24, that is for certain.

Vic