K3DS is the newest working 3ds flashcart from k3ds team, its the world's first 2in1 3ds flashcart that allows you to play 3ds games within one signle gamecard, this breathtaking card has a DS mode flashcard in combination with the revolutionary features of the 3DS mode, users only have to take one gamecard in the future. As we know, the gateway 3ds and the other 3ds flashcarts include two separate cards.
And K3ds flashcart is much easier to use since you don't have to drag at least two cards for activating 3DS Exploit and using both DS and 3DS mode. What's more, the K3DS has just released the FAQ list and users will be able to play games on DSi/DSi Xl. To make switching between both worlds as easy as possible, the team provide a built-in button to switch between DS and 3DS mode. And the emuNDND feature of K3DS allows you to play 7.2 version 3ds games on lower version console.
Gateway 3ds flashcart is generally considered as the best 3ds mode flashcart on the market, but once k3ds released, I think it will be a better option out there.