::nod:: Yeah, the WalMarts in my area sell those lights, but they still want like 20-30 dollars each for them..which I why I mentioned that CFL's are much, much cheaper.
Though I haven't actually had the pleasure of growing with LEDs yet, I do try to keep up on all the information I can find. From everything I can see, the 2 major advantages to LED are...
1) Being able to get your lights so close and positioning them for side growth.
(For the most part you can do this with CFL's too and they are also pretty good at promoting short internode distances)
2) More useful spectrum output.
(I'm not really sure you can find anything with a better spectrum output than LED...because you can literally make LED lights in nearly any ranges you want. I believe this is the aspect that helps LEDs produce the rockhard nugs that some of the mega growers show off when using them.)
I don't really see LEDs as using less power....maybe for seeing, but not so much for growing. The only reason I say that is because if you were to switch from 600w HID, you'd probably still want at least 600W of LED, or a combo that added up to that.
Even if someone designed an LED that was 5x as efficient as HID (doubtful anytime soon), then people would still shoot for the same wattage in LED...just so they could get 5x the light for the same wattage.
I'm not sure what those bulbs you posted cost in your area...but I can almost guarantee they cost more than 2x 26W CFL's...probably more than 2x 42W CFL's even. If you just want more power, go with lots of CFL's instead of LED...or check Ebay and similar places for HID lighting (I picked up a 400W MH a while back for 40 bucks, complete with light and a money back guarantee).
If you are really just wanting to experiment with LED lighting and have a few bucks to burn, then give it a whirl.
In the end, if I were to use a combo of CFL and LED, I think I would use my CFLs for main growth purposes and use the LEDs for side lighting. Might even be able to stuff them right into the plant to really get that internal/under foliage.
I think the LED would be more useful for flower than growth though, since CFL or MH lights can do the growing fine and aren't that expensive if you look around or enjoy playing with electricity. For flowering, I could really see how a more efficient spectrum use and the ability to get so close to plants could make for some buds you could use beat a man to death.