I too have an automation control system on our electric heat pump. I have learned that if I set back the thermostat at all more than 4 degrees in any zone, it costs me $$$. (Unless I am gone for more than 24 hours.) Now we have a Carrier Infinity Zone System designed specifically for our equipment, sounds like you might have a whole house security/lighting/etc... type, or what I call a load shedding type system.
We use our "set back" for more of a comfort setting, than an efficiency setting. We like it cooler at night for sleeping.
Taking into account that todays systems are alot more efficient than the systems produced pre-1992. It is my feeling that it costs you a lot more to set back a thermostat more than 2-4 degrees than what is worth. In theory it sounds good to set a thermostat back, but by the time your new "High Efficient" system heats up or cools down all internal walls, furniture, etc.... (let alone the space) you have used up all those $$ you saved for that 6-8 hours you were gone from your home with a lower thermostat setting.
Our control system lets us program what outside temperature that the electric heat strips are allowed to come on to help supplement the heat pump. We have set this at our "Balance Point", (The point at where the heat pump no longer is able to heat the home) which is at 22 degrees, in our case.
In my opinion, if your system is sized properly, your balance point should be somewhere between 15-25 degrees outdoor temp.
As for you initial question, the hotter outside it gets during the summer, the higher the amp draw is on the compressor. As for the winter, the same is the norm, but after a certain outdoor temperature, the compressor should maintain a given amperage. Keep in mind that at your balance point the compressor should run continuously with the electric resistance heaters going on and off with a call for 2nd or 3rd stage, unless your control system keeps the 2nd (and/or 3rd) stage on until the call for heat from the thermostat is gone. (then the compressor will also shut off).
Good luck, and hope this helps!