Lots of guys are using Seiko robot servos in Giant scale planes for the rudder. It delivers over 1KG of torque, but you need to drill some cooling holes to get reliable performance. These servos are used instead of a bunch of 8711's or 8611a's ganged together.

Also, Futaba has a new 9156 (I think) which has a lower torque rating, but is ROCK-SOLID and does not blow back. It has no slop and is quickly becoming the servo of choice for 3D and aerobatics in GS planes.