OK, my two cents.
ALWAYS use two servos, never one and linkage. If you have a computer radio, mix the second to the throttle as master. Makes much easier adjustment of idle through full. Can use exponentia to sync the engines by controling and matching one to the other. OK, more? Now mix the engines to the rudder, but never allow this mix to work below 50% throttle position. Is dangerous for taxiing if you do.
This makes knife edge and spins much easier. To get out of a spin, simply reverse the rudder and the single engine guys wonder, how do you do that.
I have even put the Hobbico Aero gyro in between the receiver and the two throttle servos to stabilize a hover, but I am nuts too!!
There have been numerous posts in the past on this subject, and you can use the search to find more,but have fun.
Good Luck,
Twinman