Great review and discussion. DM Training and Rifleman training is one of my babies as well.
You brought up some great points that arose in the class: I try to emphasize as strongly as possible about the importance of having a quality optic mated with a quality mount, that is attached securely, for the reasons that are clear when you read that AAR. Some people think that means to crank down on the ring screws with lots of force, but it does not. I personally use a torque wrench and look at the recommended specs for the screws based on length, diameter, and thread pitch/surface area, along with Blue Loc-tite 242. Cross bolts for the mount base are tightened with a torque wrench as well. I use levels to get everything set up so windage error isn't a factor of scope cant.
If it comes down to it, I would invest in quality mounts and optics over a high end barrel if you're really on a budget, especially with 5.56/.223 Wylde. There are plenty of barrels that can be had for a decent price. What I have seen over the years is that cheap scopes simply break. They are not worth the money wasted on them. Save up and get something solid that will stand the test of time.
Sounds like a great course. I talked with him at SHOT last year a little, and he's a very approachable, professional guy.