Steve, Kenneth has, to put it very mildly, disavowed much of his previous work. I have yet to check out Cardio Code, may do so at some point, as I've heard some good things about it. If I do, I'm sure I will get some useful things out of it, but I doubt it will replace what I currently do.
I have gotten a lot out of swinging, snatching, deadlifting, and other things that Kenneth does not currently endorse. My health is, by any measure, excellent. I'm always willing to learn from new sources, but I also filter that through my own experiences as well. And it's not uncommon that I can learn a lot from a person or discipline, without necessarily witching over to their methods. For example, I have taken a few lessons with GS coaches, and although I stuck with hardstyle lifting, not GS, it was still an invaluable learning experience that helped me enormously.
Similarly, I've learned a ton from your posts, even though our pursuits are very different.
IMHO, the first question to ask is goals, and specifically how good at what do you need to be? If you need what traditional cardio, interval training, etc., brings to you, then do what you need. For general health and well-being, I feel like a relatively few, well-performed kettlebell swings are sufficient.