Hi Philip,
I use ailevons on my H9 Pizazz and it does help with torque rolls and hovering in mild turbulence. Combined with flaperons it gives a lot of control authority to counter buffeting. I find that a torque roll can be stopped by a blast of turbulent air, and sometimes using ailevator will get it going again nice and quickly. It does markedly increase the general roll rate too. For hovering and TR's in complete calm though, I turn off the flaperons and ailevons because I want the purest control inputs for the most accurate hovering.
The 9C has a built-in ailevator mixer. You can just use this but it's not possible to assign it to a switch, it's either on or off, and if it's off you have no dual elevator movement.
I much prefer to control ailevator with a switch and here's how to do it. First of all leave the ailevator mixer inhibited. Plug in the second elevator servo into channel 5, 7, or 8. Don't use 6 or 9, six is for flaperon, 9 is just on/off. Let's say channel 5. So you have the left elevator half plugged in channel 2 and the right half plugged in channel 5. Use Programmagble Mixer 1 to slave channel 5 to channel 2 and turn the TRIM field on. This makes the slave move to the master's trim adjustments, something you want. One of the nice things about this arrangement is that you can use servo reversing, endpoint adjustments, and sub-trim adjustments in the radio to get your elevator halves to move equally. This alone is worth it even if you go no futher and have no interest in ailevators. No need for an additional Miracle-Y harness, and advanced servo control. Set it to a switch, but use the NULL switch position. This keeps it on all the time, something you want. Now to get the ailevator action, use Programmable Mixer 2 to slave channel 2 to master channel 1, then use Programmable Mixer 3 to slave channel 5 to channel 1. Set BOTH of these mixers, #2 and #3, to operate with the same switch, thus giving the illusion of a single mixer slaving two servos to the ailerons, but in actuality you use two separate mixers on one switch, and adjust them both for the same % of throws. If you adjust one mixer for more or less mixing, adjust the other. I just turned them both to 100%, and the + or - will depend on your servo geometry and pushrod positions. This method lets you turn it on and off with a switch. It's very interesting to see the results. The prop blast is swirling as it goes down the fuselage and when it hits the stabilizer it does not really hit them exactly the same. So when you move your elevators in ailevator action, you don't get equal and opposite elevator deflections which causes a little bit of pitching now and then with application of aileron and ailevator, but in the wind it's barely noticeable and makes TR's possible in a little wind. -Tom