I was at a lighting store last night (the best I've visited), and looked at both xenon and LED. The representative says he has xenon at home, b/c the LED technology wasn't there when he bought his undercabinet lighting. One thing he has noticed is that over time the xenon light gets weaker, and there is a yellowing effect. So, he replaces the bulbs even though they aren't burnt out to get the crisper light. He also says they still do give off heat ... they're not the cool alternative some thing they are (though of course they are cooler than halogen). He did say they are a good product, all things considered. But, he's now recommending the LED for undercabinet (but not in-ceiling) use. The light is beautiful. The installation is as low-profile as I've seen, and the energy savings are nothing to scoff at. They're not dimmable, yet, though he says the manufacturer (of the switches) is working hard on this, and expects to have something soon. I'm now seriously leaning toward the LED for undercabinet lights, including for my floating shelves, which I didn't think I would be able to light until now.

The only way to compare light output is to look at the lumens(or some other measure like candela) instead of the power consumed. Many vendors (for both cfls and led) just give the power equivalent without a corresponding lumen number which may be considered deceptive. Halogen bulbs run hotter than the regular incandescent bulb.

While I would now go with LED's instead of Xenon puck lamps, at the time, 2006, they were very rare, if available at all,so we went with Xenons, alto we do have some Halogens, "here and there". While both Halogens and Xenons do get hot, the Xenons do not get near as hot and it will NOT! hurt a Xenon lamp if you handle it with "bare fingers" (course only a cold lamp), but were you to do the same with a Halogen lamp, it would INDEED shorten the life of said lamp. There is no warning on Xenon lamps about handling , like there is on most Halogen lamps. Also the average life expectancy of a halogen lamp is 2000 hours whilst the life expectancy of a Xenon Lamp is 10,000 hours (5 times the life)! I back lit the Onyx surround for our gas fireplace with Xenon lights as it's a pain to change one , should one ever blow, so far in 6 years none have, but neither has any of our Halogens---but----all these lights are on dimmers and very rarely are they turned all the way up. Today, 2012, I would go ALL LED's, and in fact I just replaced the 8 can lights, 35 watt halogens in the kitchen with 8 watt LED's and they are actually brighter than the halogens were, and doing a "little math" (8 x 35 = 280 watts) (8 x 8 = 64 watts) So we are saving over 200 watts here, assuming that all were run at "full brightness" which they rarely were, but our "Before Electric Bill" was typically in the $60's range, the last bill (after switching to LED's) was $51. Good luck with your project! Gary

A low voltage (12 V) filament can be wound to a helx, then the helix wound again without any problem wioth flashing over. A 120 V filament requires a greater spacing from turn to turn to prevent flashover. I have removed multiple 120 V undercabinet systems and replaced them with 12 V systems after very short bulb life from vibration. The life of a 12 V and a 120 V bulb would likely be pretty close absent vibration. The normal activity of loading dishes and such into the cabinet above a 120 V puck light has repeatedly resulted in very short bulb life. The bulbs in high vibration applications are almost always lower voltage since the filament can be made stronger without risk of flashover. I have another house I just purchased that the 120 V pucks are about to be removed from. They are HD junk.