Me....I'm about 400% more efficient on GTD. I'm a special education teacher, and I used to have to look for one piece of paper for 2-3 days sometimes. Now....I rarely lose papers...I can find most within 5 seconds.
Also, my desk is way less cluttered. I'm now known as the "clean desk guy" at work, and people marvel at "all of the work that I get done".
I am way less stressed because I rarely lose things, and I capture everything in my Olympus Digital Voice Recorder. It gets real full sometimes, but I do get it all!
How much more efficient are you on GTD?