Dan, I'm not sure I can agree with your premise here. Yeah, sure, a Fundies class will teach you some things that most mainstream agency classes won't necessarily cover. And those skills will better prepare you for diving more efficiently and comfortably ... but in the context of diving with other people. But Fundies doesn't teach you rescue skills. It doesn't cover navigation skills. And although it does train you how to handle failures, it doesn't really cover failure-avoidance any better than traditional training ... which is to say, barely at all.
Fundies does ingrain a mindset that makes team cohesion the first option to solving any problem that arises during a dive. And in that respect, it can ... and in some respects does ... inhibit a self-reliant approach to diving ... at least in terms that a solo diver really needs to apply it. This is why, I think, solo diving is anathema to the DIR approach to diving in the first place. The two are really separate "languages".
Diving's all about muscle memory ... and that includes that big, gray muscle that sits between your ears. When you've trained and practiced and focused to dive as a team, what you've learned isn't necessarily transferrable to solo diving ... because there's more involved than just having solid diving skills. The ability to manage a problem is as much about a diver's personality and mindset as it is their training and skillset ... and in this respect, DIR training doesn't really prepare someone to be self-reliant, at least not in the way a solo diver needs to be.
The difference is primarily whether you think "team" as first option, or "self" as first option ... and that's a difficult switch to turn on and off. And how you think about your dive very much influences how you plan and prepare for it ... not to mention how you choose to execute it, and where you set your "triggers" for deciding whether and when to either thumb it, or not begin it at all.
Where I think solo training could benefit from more of a DIR approach to training would be in the implementation of failures into the open water portion of the class ... and that would include failing a student who isn't able to demonstrate the ability to get themselves out of a situation that involves multiple failures and significant task-loading.
Solo training just shouldn't be handled like OW and AOW ... where an instructor goes through a checklist of "skills", pats you on the back and hands you a C-card. You should have to demonstrate that when the hit fits the shan you're gonna be able to sort out what to do, and do it in a manner that gets you to the surface safely without assistance ... because when it does for real, you'll have to ...
... Bob (Grateful Diver)
