Same subject was beat up over on Helifreak. Some there use a combo of pinch and thumbs. Some would place their thumb on the top of the stick and a forefinger mid stick. I started out with thumbs on airplanes, switched to pinch when I thought I was going to be a heli pilot and used it successfully and now back to thumbs after giving up helis. I have to say that thumbs gave me faster movement with slightly less precision and pinch was more precision with less speed.

So with the above said.... If you are an aspiring 3D pilot I'd go with thumbs. If you decide precision aerobatics trips your trigger then pinch is the way to go. It's not a big chore to switch methods if you switch from one to the other. A week or two is all it takes to become comfortable with the other method.

Long story short..... Do whatever feels good

Ken