Hey Steve, this is an awesome topic. I have asked myself the same question, and I am interested in hearing what a strut company says about this. I understand the working harder part, but I just don't know what part of the strut wears out faster (if it actually does).
FYI - I owned an Escort before the SVT. I put Eibach springs on the car when it had ~45K on it. I later sold the car to my brother w/ ~98K on the clock. At about 100K, he put on some Tokico struts, for the stock struts were finally feeling a little soft. That's about 55K on Eibachs and stock Escort struts.
The SVT comes with Tokico struts...pretty nice struts if you ask me, and they're certainly much more performance oriented than any other Contour's struts.
My theory - Although the struts might not be the correct dampening for stiffer/lower springs, the strut will not wear out any faster.
