I use my Vamo only with single 350
batteries in short mode, and operate the button with my middle finger. (There's an opportunity for a joke there, I think, but I'll pass.) Sometimes I'll switch up and operate the button with my index finger.
Works perfectly for me in short mode, and the long mode is too unwieldy. My hands are too big for me to grip the Vamo in my palm; I hold it in my fingertips. In long mode it's just too dang heavy. In short mode it's the bomb.