Forgetting for a moment the tiny bit of difference the position of a shock would make to a bike's centre of gravity, the bottom-line is that the position of the shock itself has virtually NO impact on the suspension OR the way a bike rides.
A shock absorber is just that... a unit designed (in the case of a bicycle's suspension) to control the rate of up and down movement of the wheel. But NO bicycle shocks (rear at least) actually do that directly.
The wheel travel (the up and down) is actually connected to the shock (that unit that controls the rate of up and down movement) by a series of linkages OR, in the case of some rear designs that make it look like the shock is "directly" controlling the wheel travel, by a swingarm that is, in effect, a linkage affecting ratio and direction.
This is why a bike with 9" of rear wheel travel probably has a shock with only 2" of "direct" travel in it. i.e the shaft actually only moves in and out of the shock body 2". It's the "linkages" (regardless of what form they take) and the way they connect to the shock that actually controls the rear wheel movement and the way a bike rides... not the position of the shock itself at all.