It's real simple.
You know what you want for yourself and your son out of martial arts training. If you're getting that -- than the school you're in is good for you.
McDonalds isn't bad food. It's not great... but, y'know, there are times when I want a Big Mac or Double Cheeseburger. And there are times when I want filet mignon or just a good steak.
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I don't disagree with the sentiment here, but I think the choice of metaphors is particularly telling.
First, if you know what you want and think you're getting it, but aren't, you're in trouble. That's what a mcdojo does. It doesn't give you what you think you're getting. McDonald's IS bad food, by any definition of the word. It's unhealthy and often unnaturally processed. And these days, it's even more unhealthy than ever.
But when you eat a big mac, you know it's bad for you. Most mcdojos are like the grilled chicken. It's chicken. It's supposed to be a healthier alternative. Surely, if I eat the grilled chicken, I'm okay. Right? Unfortunately, the grilled chicken club sandwich is as bad for you as a big mac and still almost 30% fat.
Point being that a mcdojo is a business first. Profit uber alles, and, just like McD's, if the product can be shaved a little here, sliced a little there and corners cut to increase the profit, it will often be done even at the expense of the customer.
Final thing is the comment: "As long as you're getting that." Often, with regards to anything, the customer isn't educated enough to properly evaluate what they're getting. Where the vendor is also the only expert, there is a conflict of interest. If the OP is being told only by his sensei that he and his son are learning practical SD, there's a problem.
EDIT: I was with the OP until I read through the thread and saw him repeatedly mention SD techniques. As you said, it's impossible to evaluate his training without seeing it. I'm not saying differently. What I'm suggesting is that the OP is not a credible judge of what his own training is, and in the absence of a credible judge of the quality of the training, but accepting that this is admittedly a mcdojo, I see no reason to presume it is only partially a mcdojo.