Where the illumination is pure, from my ceiling, the choice is not complicated by a color-filtering nature of some lamp/ bulb holder. One 6" Glimpse at ceiling center gives very useful office illumination, beaming down onto my desktop, and bouncing off walls. I like brightest illumination, and do not consider a 4" Glimpse for this application. In a 9' by 10' room with 96" ceiling, one good light is quite enough.
I have dutifully tried 6" Glimpse lights of the three color temperatures, in the overhead light of my home office. I hoped my decent Canon digital camera, and professional computer software would allow comparisons to share, where I have photographed the light, then cropped zoom-in on light lens alone. My software fails in this. The three samples are found equal. Room illumination by the three lights is NOT equal. I get used to each, but prefer the illumination of highest color temperature. The 4000°K highest temperature also is most satisfying in rendering my understood color of walls. Surprisingly, walls at 2700°K illumination are yucky. One blog commenter wanting 2700°K lights gave me a bias toward "warm" coloring. I now do not think 4000°K coloring is cold. I fear the choice will be different for individual preference, perhaps flipping as one chooses new wall color.
JPEG photos of the three color temperatures are distinct at least in an aura about the lens. I am used to lights of 3000°K in all other rooms, and upon leaving and return to my office, find the 4000°K light is harsh. I have swapped back to 3000°K light, ending the experiment. 3000° is comfortable. I don't notice walls as yellowed or glaring. I will not ponder the decision again.
For others too, I think 3000°K is a choice you will not regret. I think most of us will want consistent lighting, the same color temperature in all rooms. Just choose the size needed. 4" for spots. 6" for work areas. 6" with a dimmer in hallways, where you sometimes need brightness, and sometimes want a night light. Maybe 6" with dimmer over a kitchen sink needed as a night light.
I wonder who is responsible to aid this consumer choice. Does every product have to be offered with color choices? Can a generic store display inform the choice, such as these at my Home Depot:
I take these displays to be of 2700°K, called Soft White, 3000°K, called Bright White, and 4000°K, called Day Light. Can't we choose consistent names? Or, might we avoid debate where with a plate light, a spectrum of diode phosphate coating color might be applied? In a 4" Glimpse, there are 18 diodes. Why not apply a sampling of the three colors. or a fuller spectrum, arranged appropriately?
Why must a fixture have only one diode color? This is Warm White 3000°K, and it is interesting that diode phosphor coating color is related intuitively to illumination color.