I purchased the Tanda acne and regenerating light therapy device back in 2008 before it was FDA approved in the US (it is now though),
Interesting that you are a new user since a few days ago, and that you seem to overwhelmingly refer in glowing terms to a single product.
I am way behind the times on this one. Doing a search on Amazon shows that there are many devices on the market that are based on this technology: Verilux Clearwave, Clear Rayz, Tria blue light system, BrightTherapy trident, acne 415 blue light therapy, Tanda Zap, etc. There are so many! They all seem to be based on the same science.
Doing a pubmed search shows that there's scientific evidence going back a decade that this technology is effective. Lots of papers - many use a specific brand and model of device.
Some issues I have with some of the devices above:
1. LED's are super cheap because they're mass produced in huge quantities. So why are all these devices so incredibly expensive?
2. Some of these devices try to force the user to upgrade the LED's while they're still useful. LED's last a very long time. The cynic in me is reminded of the shaving business model - where you make much more money if you can keep selling consumables.
I'm trying to get hold of a standard screw in globe containing high powered LED's direct from a lighting manufacturer. It's much cheaper than the stuff listed above and has a much stronger output.