i have done my only nitro plane (building a second, gp rapture) in blue/white on top, orange/white on bottom. fuse/tail were white cause i was to lazy to spray paint them (it was windy the day i was doing it and i was getting grass/dirt sticking to the paint) anywho the combo has worked well, im doing it again on my rapture. i would have thought that you wouldnt have been able to see the blue/white, but when the sky is blue you see the white. when the sky is that greyish color the blue helps the white from blending in.
as for the orange/white i actually have a harder time seeing it when its cloudy for some reason the orange looks more dark grey than orange. however its not bad enough that you would loose it. and in the sunlight if you miss the orange you might need to get your eyes checked.