I noticed no change in ride height when I did this, and I don't recall any reports of such from others.
It may not be a bad idea to do the fronts too, but changing to stiffer rear shocks is what fixes the pillow on wheels feeling. Most of the fault is in the stock rear shocks, especially when worn out.
The part I suggested is meant for the 2000-2004 version of the car. The size and fit is identical, but the guts are set up to be stiffer. This is what eliminates the pillow factor.
Just by changing the rears, the car will seem considerably firmer and more sure-footed. It may even be a bit on the harsh side for the first week or so, but it'll settle down. I still have the stock front struts.