The ordinary Futaba with ball race (3004) that was fitted to mine was just not strong enough to either pull in or hold in when there was enough wind to make it really go, so I got a high torque one, of the same physical size, from Howes (Power HD 2400A). I had to make a new sail arm from ply, as the splines on the Futaba horn were not a good enough fit, and the arm was unwilling to mount on the new horn due to a large locating lump. I also had to rewire it as the existing wiring harness had passed its sell-by date with the increased demand of the new servo.
It has a 90° throw, but I rigged it so that fullest out is at 90° to the centreline, and fully in is facing forward. This is not as the instructions show, but I feel it gives better pull when close hauling, and probably takes a lot less effort to keep it there. What is lost in travel is fairly insignificant, as when fully out, the sail brushes the standing rigging.