Well I thought your question was pretty clear.
"Which one to buy?, ACE or Robbe?" Robbe is the current favorite.
As for Dual throttle set up vs twin Joystick, I opted to stay with the dual throttle.
The Voith schneider drives can provide 360 degrees thrust. Having each drive on a joystick would have been very tactile. However after seeing how others had set up their VS drives on the dual throttle and rudder configurations, I found it was much simpler.
I find with my Voith Schneider drives, that it is convenient to put my thumb across both throttle sticks(while one is forward, and one is in reverse) and nudge them forward and back to get a complete sideways movent with the boat.
With the dual joysticks, there is the possiblity of nudging that right engine throttle when you move the rudder, and that could cause the whole boat to rotate during a lateral movement. And if you are trying to stop a slight forward motion, while attempting to move the boat sideways, the throttles need to be nudged an equal amount toward the reverse. That "equal" change in throttle for both engines is not impossible, just a little more difficult using dual joysticks.
Does what I am saying make any sense at all?[&:]
There is no reason why you can't use standard dual Joysticks.
It is usually personal preferance for most modelers.
If you learned on dual throttles and a rudder control, you will handle your boat best that way.
If you learn on dual Joysticks you will learn to handle your boat just as well.
Umi
(Of course I know lots of people that can't drive their boats no matter what configuration they use.
)