I would appreciate information related to thermostat settings. We have a ClimateMaster TTV072 6 Ton unit and we are in a cold region (Ontario, Canada). Is it more energy efficient to use a 2-3 degree offset to go to stage 2 or a lower offset? Right now the installer set it to go to stage 2 almost immediately. Would it be more energy efficient to use a higher offset? Our cost for electricity is quite expensive (up to 15 cents / kWH).

A 2-3 degree (Celsius I assume) setback (offset) seems like a lot to me. As long as:
you auxiliary heat doesn't engage during recovery (eating up any potential savings),
you don't mind possibly long recovery times and,
you are comfortable, then you can set back.

First stage in a multi-stage compressor is typically more efficient than second stage, but savings from the setback might offset the use of second stage to recover.  Too many variables to tell for sure.  I setback 2F and run second stage to recover (no aux.)

Posted By geome on 22 Feb 2011 09:35 AM
...   I setback 2F and run second stage to recover (no aux.)

I do the same, I turn the system down 2 or 3 degrees F at night before bed, do not turn the system back up until I return home from work at 6pm the next day and I have the AUX heat disabled. I only have an one stage system. 

I think the OP is talking about how many degrees room temp must drop below the thermostat's setpoint before the second stage of the compressor engages, rather than how many degrees to turn the temperature down at nighttime.

Yes, it generally would be more energy efficient to let the compressor run longer in the higher COP stage one before it kicks into stage two. The obvious downside of this would be the house getting a degree or so chillier before stage 2 kicks in. From what I've read around here, there also could be some debate about whether wear and tear on the compressor is worse from excessively long runtimes in1st stage vs excessively short cycles from putting the heat pump almost immediately into 2nd stage.

No debate about that - long runtimes are far less wearing than on / off cycles.