A chokehold is preventing a creature from breathing. A sleeper hold is preventing blood from getting to a creature's brain. It seems to me that RAI are that whatever terrible thing your going to do to a creature, you need to do in the 1d4 rounds they are unconscious. Dropping a creature's HP down to 0 with the Sleeper Hold feat would be OP IMHO.
I would agree that Kraken Throttle is more along the lines of Chokehold than sleeper hold.