I have both kites, and would keep the Kaiju over the 4d. Both are small, but the K is a little bigger. The K is also a little easier to get tricks out of. Neither kite is appropriate for winds over 5mph.
Neither kite is a favorite, just because of their small size. I prefer a kite to be 7' or larger, smaller kites just feel like toys to me. But... that's just me. 😎