FWIW, I took the knife course prior to CQPC (their empty-hand course). In hindsight, I kinda wish I'd taken CQPC first. Geo speaks truth.
Then again, I had close to 300 hrs of pistol training (not all of it at TDI) along with TDI's knife and impact weapon courses prior to taking my first empty-hand course, and I rather wish I'd started with some form of empty-hand combatives far sooner. I feel like I'm playing catch-up. I've taken their CQPC (taking it again this weekend), and another school's empty-hand course, along with starting up twice a week at a local (softer) MMA dojo.
Like many gun owners (including the subset who understand the value of training), I came in thinking that personal defense begins and ends with a gun, or another weapon if you happen to be without a gun. A weapon only stops a threat if you have the time and distance to deploy it, and if I have little clue how to create that space and/or buy sufficient time, I can't make use of the asset. Also, someone much smarter than me pointed out that, if all you have is a hammer, every problem looks like a nail. I like having a few more choices now.