As an attendee, my personal data might be relevant:

I have gained practice deliberately acquiring new habits and soliciting useful feedback. Before camp I had no specific plans for self-improvement other than "work harder", and now I actually keep track of what works and what doesn't. For instance, I am deliberately improving my public speaking skills by giving talks on Minicamp material once a week to a limited audience. I would place a bet that the "alternate universe me" who instead attended Inspirational Retreat X (IRX) would not have had lasting effects nearly a year later.

I am deliberately extending my network of contacts. Speaking to new people was a skill that I didn't have pre-Minicamp. On this point, "alternate universe me" could have reasonably acquired similar skills from IRX, but I have relatively strong reason to believe that those skills would be much more of a black box than they are now. I usually leave workshops inspired, but I can tell if it's a poor workshop when I try to apply the skills I learned and discover that it's not as easy as it seemed to be according to the instructor's examples. There is a difference between "explaining something so that it sounds good" and "explaining something so someone else can do it". I attend swing dancing workshops about once a month, and Minicamp never once felt inapplicable like several of the lessons I've taken over the years. More personal data: I talked a local CEO into letting me give a presentation on rationality to the class he teaches on the side at Penn State, which is something I would have never even thought about doing before Minicamp.

This comment has already gone on too long, but I hope that gives you some useful information.

Summary: Minicamp's general perspective on teaching skills is more effective than the vast majority of small workshops I attend because the instructors taught skills rather than inspiration. Inspiration came from trying their skills and discovering that they worked, which is surprisingly rare.