The big differerentiator seems to be the type of LED used. School of thought states that while Cree are more expensive, they are more efficient and you can get a little more light with less heat. I'd check out some of the screw in bulbs if you're looking to do a pedant. Pretty hard to beat the ease of install into a standard light socket. My LEDs are on order right now for my biocube 29, so I can let you know what my experience is.
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I am here: http://maps.google.com/maps?ll=30.205091,-97.835974