For Fans of Flatpicking Guitar Magazine
I am chiming in after this post has been here several years...but this is an issue I am wrestling with. I used to anchor, but found as I sped up, my movement became exaggerated. I bought FP Mags book, "Improving Speed, Tone and Accuracy" and it discussed this issue. It favored what is called gliding or sliding, where for me the fingers are curled under the right hand and I lightly rest the pinky on the pickguard. Being curled up, my pinky rests on the finger nail...which provides little resistance as I slide up for low strings and down for the higher ones. The book also talks about the different components of movement for flat picking; from the elbow to wrist, the wrist itself and then even the thumb and forefinger moving slightly.
I find with this new right hand technique, my movement is quieter and more efficient...and I notice my speed and accuracy increasing. There is also a related youtube post that shows this in real time. Can't find the youtube, but here is link to the book.
I have noticed that others have shared what I have experienced - when it is a fiddle tune or lots of single string runs, I drop the pinky - but when its straight rhythm with strums - I go free hand. I really like the way my D-28 rings out when I hit a chord!