Hi there
To truly evaluate the difference between tank steering and mixers we must really study the history or find out where mixers came from. If we turn back the clocks to say, the early 70s, radio control gear was quite expensive more than an average weekly wage in those days. So, to get a multi-channel set they were extremely expensive costing £100s of pounds and Joe Bloggs just couldnt afford this amount of money. Along came 2 companies Hunter Systems and ACTion and going back I am unsure who came up with the mixer first it may have been Hunters? But correct me if I am wrong. Me half tea leaf will come in here maybe
The idea was on a 2 channel radio set, one with rudder channel and the other was the throttle. This was great for the average person with a single prop boat. But, when you come to multi prop boats that is when the problems of a single channel became apparent. The way round it was you could use a Y lead with 2 speed controllers obviously one speed controller for each motor but this did not give you independent control of each motor. Some of us used to wire up micro switches around the tiller arm of the rudder so that when you put the rudder hard over to say, port, it came into contact with the micro switch which was wired up to the port motor either switching the motor off or, if you were really clever there was a resistance wired in so it cut the motor to half speed. As you can imagine all of this wiring took up space and was fairly complicated until, as I say the mixer from ACTion/Hunter which combined your rudder with your throttle channels electronically in a little box. Giving some variable speed. A lot easier to wire up than the micro switches.
Now, the design of these mixers stayed basically the same for a good few years, but as we move into the 90s Robbe brought out the Robbe F14 super twin stick handset again this cost some money but also gave independent control of twin motors through a split joystick.
Now we move on to the age of the cheap transmitters which we are in now where we can do built in mixing on our transmitters. There are some down sides to this if we take for instance the mixer a P94 from ACTion it gives you several options built into it such as tank steering, percentage control of speed and so forth but, this only takes 2 channels up from your transmitter if you use a Y tail mixer you have to use 3 channels on your handset one for each speed controller and one for your rudder. This is where the Ytail does its mixing and its the same problem if you do the mixing on the handset as well through programming you use 3 channels so you lose out on one channel all the time. So that is the real main benefit of an on-board mixer. (The likes of either ACTion or Hunter). Tank steering is where you still have to use 3 channels the advantage of that is if you are sailing in a straight line, you can adjust each motor slightly to correct any variation off course.
The best of them all though is what I was taught by a guy called Stan and he had an old tug called Growler and he could thrash us all on any scale sail course we put out on the lake and his words were the best thing to do is to learn how to sail your model you dont need any fancy gizmos, such as tank steering bow thrusters or mixers.
Just my thoughts
John