I never planned on purchasing the full set. I just can't do high impact stuff anymore. Which all the current leg workouts are pylo/leg stuff and then the high impact cardio. I will more than likely ended up with the upper body weight work and the low impact hiit. I really wish I could buy a whole set and actually get to use them all. I guess I could buy at the discount price but then I would end up with a lot of stuff I just can't use. I'm to anal to have shelf of stuff I can't use LOL I have some stuff I modify but it really makes a workout more fun if your actually doing the workout cathe or whatever instructor is doing. I hope that since a few of Cathe crew actually may admit they are getting older LOL I get Cathe maybe 50 and she does have the nice aerobic floor and from previous video looks likes she has already had some knee surgery. I would rather step back a bit instead of heading to future surgery. I believe Brenda has had hip surgery. I do like Cathe low impact workouts but not having all with a modifier limits what I purchase..
This is not a cathe bash she must be successful with the status quo so I'll just pick and choose those workouts that work for me.
A little myth busting here. I know it's a widely held belief by many that Plyo activities cause most knee issues, but research doesn't back this up and in fact shows the opposite in many cases. Plyo is one of the things you need to develop stronger bones. Without weight bearing activities and a certain amount of stress you will lose bone mass. Sitting too much for most people is a much bigger cause of knee issues than Plyo aerobics.
Lack of stress on bones is a major problem for astronauts staying on the international space station and a reason why they lose bone mass. Likewise, lack of stress on your bones back on earth is a problem too. I know most people like to blame their bad knees and hip on too much running or high impact aerobics, but research doesn't support this.
You mentioned Cathe and Brenda and problems they have had, but you have some of the facts wrong which paint a different picture when you know them. It is true that Cathe has had two knee operations, one major (torn ACL) and one minor (Plica Band) operation. The major operation wasn't caused by high impact aerobics. Instead it was caused by a low impact activity (skiing). Cathe's other knee operation was a problem with her plica band. Though the cause is unknown, her problem was probably caused by twisting and turning or a change in here gate caused by the first operation.
Everyone's frame will change for the worse with age, but Cathe at the age of 50 can still out jump and out run most 20 year old's. If Cathe could go back in time and eliminate high impact aerobics from her life she would not be better off than she is after doing Plyo for over 30 years. If you watch Cathe Live you will see several class participants that are in their 60's that have been taking Cathe's class for over 30 years and they're still doing just fine and in much better health than those who haven't done Plyo classes. The people hobbling around town are not doing so because of too much Plyo aerobics, their problems are more likely related to body inflammation, obesity, lack of plyo and resistance exercise and other causes.
Also, Brenda's injury was also not related to Plyo aerobics. She was injured in a Triathlon. Brenda just competed again a few days ago in another Iron Man competition and did very well. She too is in far better shape from doing Plyo activities than those in her age group that do not do high impact exercises.
At our health club, where we see up to 1000 people in a day, and have done so for over 30 years, we also don't see evidence that people who do Plyo activities have more knee issues than those who don't. This is further backed up by some studies on runners that show no evidence that runners have more knee issues than non-runners. Though high impact exercise is often blamed for causing knee problems there are other factors that are more likely to cause osteoarthritis. If you have osteoarthritis, talk to your doctor before doing high-impact exercise, but high impact exercise in moderation appears to be beneficial for those that don’t suffer from severe osteoarthritis.
I don't know in your case if you have osteoarthritis, but if you do you will certainly need to find alternatives to high impact exercise. I just don't want people to think there is a cause-effect relationship to Plyo aerobics and knee problems. It's one of those myths that seems to stick in our industry.
We have some excellent Blog post articles on this subject, including this one that you might find interesting:
http://cathe.com/the-effect-of-high-impact-exercise-on-knee-health
Hope this helps bring a better understanding to this subject.