@Robert, I know several people who have them and really love them. One, in fact, devotes one of his kettles to the Fire Butler. Along with the extended cooking time and larger cooking surface area, one thing they all like it the "hibachi." They use it for everything from a nice stir fry to old fashioned flat top burgers to fajitas to a traditional Philly cheesesteaks.
I agree with a lot of
@Troy's points. For me, it's very expensive and very cumbersome if you are not going to dedicate a kettle to it, which I cannot do.
The TTT is a different story. I gave my son-in-law one for his kamado and he loved it. He did some of his best competition pulled pork using it. He sold the kamado to get a pellet-pooper, the TTT went with it.
After reading some of the comments here, I'm thinking about trying one, even though I do a pretty good job of maintaining temps the old fashioned way. After-all, they're just $20. That's less that a fifth of scotch . . . . .
BD