There has been some research into ejector seats and it all hinges on the guarantee of getting all of the blades off in sequence so that the out of balance forces don't get you before one of the blades left attached will.
Horizontal ejector seats are again not possible because the human body would not survive the acceleration.
IIRC the body can survive up to 45g in the vertical plane but only 5 to 10g in the horizontal. Most current ejector seats go out at something like 40g.
Even with the correct seating position and everything working properly you are going to lose around 2 - 5 cm in height in a successful ejection!