Sorry, I mixed up that 20% with 40%. Their claim is 40% faster. And here is their source:
Pogo Charger
"This is a pogo charger for Nexus 10. This make a nexus 10 charged 40% faster than a micro usb, so a battery wouldn?t be drained faster than being charged by a micro usb!. It will be available on Amazon and ebay soon for sale. If you want to get a notification when it is available for sale, please leave your email. Thank you."
I am not saying it is proven to be 40% faster, only that that is their claim and that they never claimed it would be twice as fast (100% faster) as you indicate. In theory, it has face validity (meaning it is not an outrageous claim). I don't care how fast it charges, myself, since overnight is overnight to me. For me, I am
extremely happy the Nexus 10 has standard USB charging and is compatible with my Anker battery pack and various other cables and chargers, without any proprietary stuff.
As for whether it is worth the money, that depends on each person's use case and expectation. Charge speed is just one factor in the several I mentioned previously:
1) It charges faster than the microUSB spec will allow. (A claim not verified by anyone yet)
2) It connects more quickly.
3) It is damage-proof if cord is tripped or yanked.
4) Saves wear on microUSB port.
5) Allows charging while also using microUSB for data at the same time.