I think I will stick with A for WB in most instances. I know you can adjust WB in NX2 very easily, but I would just prefer not to did it all that often!
That said the D300 was impeccably behaved this morning with a mixture of warm sunlight (on the left of the frame) and fluorescent lighting from the ceiling..... the image attached below had picture set at standard and auto WB.
I may well be looking at the D200 through rose-tinted spectacle as it were. I will post a few comparison shots tomorrow to show the issue.