While I was there, I decided to pick up one of the Cree 100W LED soft white bulbs and one of their 100W daylight LED bulbs and stick them into the light fixture in my office in the hope of getting reasonably balanced color. This seems to be working ok, but I won't be able to tell until I can get the fixture cover back on. The bulbs are a bit larger than the old ones. Oops.
I can adjust the position of the plate on the nipple that the fixture snugs up to, but not without some penetrating oil to loosen the nuts, which are pretty firmly stuck right now. And since I'm going to go freeze at tonight's Cubs / Cards game, that will be a project for a bit later. :)