You don't want something that automatically applies more power because of acceleration itself, or it will just ramp up to full power and stay there until you shut it down (assuming you have a way to do that).
Same thing for auto-deceleration, it'll just grind to a stop and hold there.
All you would really want is something that gives you more boost when you need it, and doesnt' do anything at all when you don't.
There are a lot of automated limiting / boosting things you can do using the CA3 with external sensors, and a fair bit of creativity and working out settings in it.
If you use just the Aux input, you can really only do one of them at a time, because it only has one aux input and that can only be used to modulate one thing at a time.
But actually it has a number of inputs:
--Analog input for throttle in (THin)
--Ebrake in (on/off only)
--Temperature sensor input (which doesnt' actually have to be a temperature sensor...it's an analog input you could use to sense anything within the voltage range...but it only gets read by the part of the CA monitoring temperatures, so it will only be able to modulate things that can be affected by that).
--torque sensor analog input (analog)
--cadence sensor pulse input (on/off)
--cadense sensor direction input (on/off)
--current-measuring shunt input (analog)
They all have dedicated purposes, but if you get creative with your thinking, and don't need them for their actual purpose, you can use them for other inputs as long as you can work out a way to make the input you want to use modulate something it's capable of modulating.
You just kinda have to know what the CA can actually do, and kinda how it does it, which is covered in the CA3 info page previously linked, and Teklektik's UUG (linked on taht page), and the CA3 beta thread (linked on that page). Just takes a fair bit of time to read, and for me even longer to understand what's going on. Even now, years after starting to use one, I'm just now beginning to understand how some of the interactions between settings work and can be used to do stuff I need it to do. (and to be certain that it *cant'* do some of it).
A torque sensor on the cranks would in theory let you get more boost on hills vs flats, or against high headwinds, etc., because you'd be pedalling harder, but I havent' been able to get mine to work like that (TDCM; also have a THUN but not on the trike); the CA doesn't appear to use the torque sensor in a way that applies to what I need, because I *only* need the torque to work at startup before I can spin the cranks, after that cadence does what I want for the most part.
It probably would do it for a "normal" bike under those conditions, so for you it'd probably work. If you are interested in trying it, I could loan you the THUN BB out of the old CrazyBike2 frame, so you can see if the idea works (it only senses the left crank, IIRC, TDCM does both). If not, just send it back to me. (if you'd pay shipping both ways, which should be cheap enough USPS flatrate PM....if you find you like it you could buy it from me cheap).