Good point, Geoffc. Part of my rational for the blinkies was for night HDR's and to quickly see if I've gone far enough on the high side. And like you point out, it's hard to get a "true" read-out for the histogram since it's so dependent upon the rendered JPEG. The more experienced you become as a digital photographer the more important the histogram becomes so I can't understand why they haven't invented some kind of RAW histogram or the like. Sounds like like method is a good one, I'll give it a try, thanks!
And back to the subject of eyedropper and WB. I'm stunned at how nicely it works, provided you can find a pixel square in the 18% gray range. Such a simple technique and I feel so dumb for completely forgetting about it. Oh well, chalk it up to age...