I picked up the AVO throttle controller about a month ago and have been testing it pretty thoroughly so here goes.
It has three mods; standard (normal), off-road (3 settings), and power (9 settings). Looking around the webber-nets it "appears" like the same product is rebranded many times for various makes/models/vendors. When I got the controller, I had to call in to get a different cable since the one provided was too big to plug into the pedal;probably for the older Subarus. These products are still being marketed only to the older roos are be wary if you order it, you may get the wrong cable for the accelerator.
Now for the good part. It does work on a fifth gen and it did increase the throttle response which is what it billed for. What you have to be careful about is while the response is better the shift points are still going to be the same. Doesn't seem like much but if your goal is like mine for smooth power delivery, it can get a little disruptive when the car shifts too early. I find myself playing with the settings moving between 1 to 4 on the power settings.
Another thing to note is while the module will retain the setting you last had it since its plugged into a 12volt source (OBD connector in my case) it does not turn the settings on when you start the car, you have to turn it back on manually.