Until my husband made me a topper for my risers, I did use my Club Step as a substitute with enough risers to measure 14 inches and it worked fine. And unless Cathe uses all 4 sides of the High Step for cardio, you can just turn your step vertical for cardio segments.
P.S. I now own the High Step and still have a homemade topper and 4 purple/pink risers if anyone wants to buy them.