Mosh is right:
If you get LEDs, make sure you get the ones with full wave rectification. Otherwise, they blink at 60Hz which is noticeable.
Don't know about that, I know how to tell electronically if I take the thing apart, but typically as a "consumer" how should I tell my wife to shop?
The other effect thats unnerving is to move your head or eyes quickly past the lights drawing them through your field of vision when they are on. You realize they aren't solidly on. SOme cars do this and its terribly distracting.
The color changes on LED's too. The purples and blues are noticeably different this year while the yellow is even more piercing.