Darnold9999:Hard question, assuming a compentent diver, i.e. someone who is at the level of DIR-F in terms of skills then it will be the tec divers that get the most benefit out of DIR diving. (Taking that DIR-F is not DIR, but a set of fundamental skills you need to get in the DIR door)
If something goes wrong on a rec dive and I am this hypothetical competent diver I can self rescue - pretty much that is the definition of a rec dive. DIR philosophy really isn't going to make much of a difference in most cases. Planning, deco, communication, etc. don't really come into play in a significant way in the vast majority of rec dives. Most can be successfully completed using the simple plan - lets go diving, come back when we get low on air.
Something goes wrong on a tec dive and all of the things that are DIR start to become much more important to your survival. The more extreme the environment the more benefit. Survival being the ultimate benefit.
Now back to the real world.
Most divers have nowhere near the level of DIR-F competence. Getting to that level of competance whether through DIR-F or any other similar training re skills is going to help the rec diver more than the tec diver who really should have this base level of skill before getting into wrecks, caves, doing deco dives etc. But as a number of people have pointed out that is not really DIR - as I understand it, DIR is more than this base level of skills.
just my 2 cents
I think we have the winner! Well put.