Earlier this summer I was doing some experimenting with alternate rudder servos for 5v and 6v systems. I ran a HS-6965HB for about a month.
It’s not quite as good as the S9254 so you have to run slightly less gain. You can run the GY401 digital mode with no problem. If you can live with slightly less holding power it is a good durable rudder servo.
Futaba has the solution to the S9254 durability problem. It’s the new BLS251 Brushless rudder servo that should be available next month. The nice thing about this servo is that it will work with the high frame rate GY611 gyro it will be less expensive if you ever want to upgrade. If you need lots of holding power it may be best to wait and get a BLS251 next month. http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXRJS3