Hi, Cathy -
I had a similar question a few weeks ago. I wasn't getting the results I wanted with the FIRM videos and I was thinking of dumping them all and buying just Cathe videos. I had been doing both, mixing them up.
I wound up keeping the FIRMs I had, getting rid of the ones I really didn't like, and purchasing some new Cathe videos.
I have been doing only Cathe videos since then and I feel my fitness level has really gone up a significant amount in only about three weeks. I can now do all the step videos on an 8" step, whereas before I could only do 6". The weight lifting portions of the videos are very challenging and thorough. No wimpy sets with Cathe workouts!
In my opinion, Cathe is also a more real person, if that makes sense. The FIRM tends to be a little phony. You just know the FIRM leads cleaning up and cooling off between segments and what not. When Cathe and her crew is lifting or jumping around, you just know they're really lifting that much weight, or working that hard without stops. And I kind of like when you see them mess up too. Plus, the women look like real women, and not the "beautiful people" you see in the FIRM videos.
The FIRM videos are good workouts, but I think the Cathe videos are just plain better.
MHO,
Susan