I recently attended an advanced Defensive Tactics course. It was rather informative and I walked away with some concepts that I'll definitely pass on.
I would like to state that when training in DT's, things may get a little rough. I expect some pain, some bruises, and maybe even some bleeding. It will happen. what I don't expect is other DT Instructors whining about people being too rough.
Seriously, I was asked to "go soft" a few times. (Generally we go about 20% of full force for training but some want even less force used.) Now, those same people would then resist the take down maneuver and laugh that I didn't have it. When I applied additional force to lock in the take down, people would get upset.
If you want to resist, really resist and don't just pretend you are getting one over on me. A few of the Instructors were very good sports and we did go at it a lot harder. We actually had to use skill in order to get down to T-3. That was a lot of fun! There was one Instructor whom I will admit was stronger and much more skilled than I was, and I had a blast training with him.
Training. Do it for real. Don't just attend.