You are correct - that Cervelo with the same stem/ setback/ bars will fit identically within 2mm of your current. You'd be hard-pressed to tell the difference.

Now, they may handle differently because of tube angles, fork offset, etc, but your contact points will be located in the same spots.

The SystemSix and the Foil are both old-fashioned long and low, which works well for some people (like me) and less well for others (apparently you). The shorter and taller fit has gotten more popular of late. This is why it's important to not fall in love with a bike before checking the geometry.