bwerb once bubbled...
...it's really quite simple. The direct answer to your question would be no. You cannot be DIR with a double-hose regulator (on open circuit).
This is not to say that you can't have a whole bunch of other great "DIR" tweaks to your gear and technique and a great mindset etc., or even that you can't be a safe, happy, great diver.
But...DIR you will not be. One of the primary tenants of DIR is that you donate the regulator you are breathing. Since you cannot by design do this with a double-hose reg, by definition, you cannot be DIR (on open circuit). This is not something to get flamed about.
I'll compair it with a rough analogy..."I'd like to become a Christian, but I don't want to believe any of that Jesus stuff."
In other words...it's kinda the foundation of the system.
Just my thoughts.