Please correct me if I am wrong, but, I would have expected more response in the image when stepping through the color temperatures - thanks Thani for sharing that. Could it be that the WB adjustment is diminished to some degree due to some other "stronger" control or compensating autoadjustment that limits the range available to WB adjustment? Disabling that control might allow for a larger WB adjustment range.
Hopefully the WB adjustment is done in the analog compontents (amplication) before the A/D converters in the camera. Otherwise, if the WB is done internally in the digital stages, there is far less latitude for WB adjustment without introducing other artefacts like banding. This is why I am interested to know how well the camera reproduces a graded blue or green water background (without any creative work in CG).
Just my 2 cents.