I should clarify WHY I said Tom Thumbs & Kimberwicke bits are evil. Frequently in training situations I see tiny kids on a horse they haven't a prayer of stopping and what's the bit I seem to always see? Tom Thumb or Kimberwicke, to give the tiny kid a hope of coming out with a whole skin. These kids tend to balance on the mouth and haul on the horses mouth for everything. SO I have an instant knee jerk reaction to those bits. I've retrained horses with really hard mouths from kids pulling on those bits and tried to get horses to lighten on the forehand who have learned to balance on those bits and pull on the little kids arms. It's a real pain.
Whoever posted that if you have soft hands the bits are not evil is correct. A bosal can be a torture device in the wrong hands and a spade bit can be just the right bit in a fully trained bridle horse.
I tend to prefer the Myler bits because the way they're constructed, they're designed to do less damage even if someone has a heavier hand.