My Take on the subject...
When I started diving I looked at everything I could find. I read everything I could find on all subjects related to diving. I found DIR and it made a lot of sense. I've studied it intensely and some things at first didn't make a lot of sense to me. Some did and I thought this looked like a good way to do it.
As I've progressed through my diving "career" gaining experience and now with Cave training and doing long cave dives every weekend I've realized piece by piece why DIR works. It's hard to know why they want you to have this and that exactly the way they say until you actually are 3000ft in a cave with double stages.... then it hits you... OHHH that's why. Little things like SS clips, position of clips on hose, etc, etc. go along with the bigger things.
Yes, you can dive NON DIR and survive and even do well BUT if you haven't been there and done that and tried DIR don't knock it because it DEFINATELY works. I know. I'm not saying it's the only way to dive but I do believe it's THE BEST for backmount diving. (Sidemount is a whole different ballgame)
Also, no where in "DIR" does it state you need to have Halcyon equiptment or GUE training. Do any of the top players in wkpp have GUE cards?? Nope. Also, some of the equiptment you can buy at Extreme Exposure/Halcyon is decidedly NOT DIR. Most is but not all. Halcyon does make the best DIR equiptment (imho) though.
The best thing to do is to learn what DIR really is and go from there. It's NOT just an equiptment configuration but a total lifestyle and mindset.
BTW: There are a lot of people who THINK they are DIR but aren't. Those are the ones you have to watch out for and usually have the biggest "attitudes". As for me, I am trying but it's a hard road to become totally DIR in the truest sense. A bit like becomming an olympic athlete. But hey, there's nothing wrong with trying.