I actually do both. I used to be thumbs only but have been learning the pinch method. Feels weird but works and I am getting used to it. I found that quick control movements would usually end up with my thumbs sliding off the stick unless I wasn't really pressing down on the stick which is bad news in a torque roll or rolling harriers.

And this is using aftermarket sticks that have a ton of deep grooves cut in the top. Dang dry skin[:@]. I use a strap to hold my trnasmitter. A good tray is somewhat expensive.

I use thumbs for when I had just putting around doing mild aerobatics and pinch when doing 3D or violent manuvers