I dont think there is an advantage to 2 servos, unless you need them mounted in the tail to balance, or unless you get a failure where the servo strips or fails in a neutral position. I have landed with 1 stripped elevator servo and the elevator luckily stuck near neutral. I dont know if you could land a plane with 1 servo stuck at or near full deflection. Granted you probably arent giong to land in 1 piece if a single servo fails in flight. That being said I have landed after one stab snapped off completely in flight and was flapping behind the plane, so I guess anything is possible.

Either way I would think single or dual servos on the CG is going to be a wash from a weight/functionality point of view, it just comes down to whatever you like.

The 2 servo setup basically will come out the same weight or slightly heavier than a single servo setup if you use 9650's (I checked before I made my decision for the DEPS, a 9151 is exactly the same weight as 2 9650's), but considering it takes 2 ball connectors and 2 rod ends to make up the 2 servo setup there is going to be minimal weight gain.

Either way using the DEPS system is going to give you clean, smooth and true elevator control. I really really like the DEPS a lot.

Just comes down to personal preference I think.[8D]