Re: why the 2.0 ltr optional engine?
Not sure where you live, but in Ontario, the optional 2.0 engine has a government rebate of $1000. You get it a few months after you've bought the car. A few people look just for that alone, because it's just more money they get off the purchase really...
I have the compass with the 2.4, and i REALLY don't think the smaller engine cuts it. For a 4 cyl engine, that's also a decent size - you need that extra bit of power that the 2.4 L provides.
The 2.0L also has to work a little harder because it's a smaller engine pushing the same size car - so gas comsumption isn't all that much better.