I have an older model KEG that I've had for about three years. I started smoking on the KEG. It does take a bit of time to dial in the temps but once you get the hang of it, it's pretty easy.
I've cooked low and slow and also high temps. It turns out some great que, from butts and ribs to steaks and pizza. It does a good job throughout the heat spectrum.
I've never cooked on a traeger or BGE but would think the BGE would cook the same as the KEG.
Note the kamado's have limited cooking space. I've cooked three butts, two on the bottom grate and one on the top, at the same time. Make sure to get a heat deflector as you will need it.
Bubba Keg / Stumps Baby / Super Fast Yellow Thermapen / Lodge Cast Iron Grill / Smoke Vault