I fly everything with thumbs. My FPV quads, wings, helis, and my Mavic... All thumbs. Just practice with what feels better to you. I have seen amazing pilots use both techniques.
On a side note I find it much easier to access additional switches on my Taranis when thumbing. An example is sliding one of FPV quads. Due to the use of airmode, the quad will bounce when I comes into contact with a hard surface as the flight controller tries to compensate. I simply disable airmode with a switch, hit the ground and slide under or down whatever the obstacle is, and then quickly hit the switch again while being able to keep my thumbs in place on the sticks when I'm back in the air. This doesn't really apply to a Mavic obviously but is an example of why thumbs works for me.