Here are my unadulterated thoughts.
High Step Challenge is a joy. It isn't as "tough" as High Step Tranining Advanced - but you can either embrace that and use it on a day where you don't want to push yourself to the max - or - you can make it tougher. I try to go as heavy as I can and instead of the band, I substitute with dumbbells whenever I can. I sometimes do the workout just as is and feel pretty accomplished.
Kick Max is a gem. I know a lot of people don't see it as very "intense" - but I think it's as intense as you want it to be. In my opinion, the DVD is worth it for the "blast challenge" section alone. The first (4) kickboxing combos are not as tough as the combos in, say, KP&C - but I think it's planned that way. Kick Max as-is is okay, but I like to break it up. I add the "blast challenge" segment to the end of a short step workout sometimes, to "go out with a ban," as Cathe says. Also, I LOVE the leg drills at the end. For me, they've really improved my flexibility and my hip flexor endurance. Also, you can make the kickbox combos higher intensity/higher impact if you like. Simply do jacks when Cathe marches - do jump kicks when Cathe does regular kicks, etc. I do, however, think that Cathe did the beginning part lower impact a.) so you could really focus on balance and really add intensity to your punches and kicks (Kick Max makes me VERY sore in the lat and ab area), and b.) so you'd have a bit of energy saved up for the blast segment.
My only complaint is I WISH WISH WISH these two DVDs came with better chaptering and better premixes!!!