I played 32K battles on mobile and if I were to switch to KBM now, I have no doubt I will play like a noob.
I tried playing KBM, and the change was so uncomfortable for me that I switched back to my iPad.
I couldn't move reliably (especially under stress, when I'm under fire, or when someone's maneuvering around me) because the way you move at an angle is to hit A-W at the same time, or D-W at the same time, or whatever. It felt jerky and awkward to me. On mobile, you just push the joystick wheel and it advances/reverses and turns that way. I have a Bluetooth joystick - maybe I should give that a try?
I couldn't aim reliably. The auto-aim was awkward, so I spent a ridiculous amount of time over-aiming, which left me vulnerable to incoming fire.
However, the video quality was astonishing on my 27" display, expansive and immersive, and my MacBook Pro wasn't taxed in any way by the gameplay. The audio was so good that it actually made me flinch a few times. It was an absolutely first-rate experience, nearly cinematic. I found myself wishing I could use my familiar iPad controls and look at that gorgeous display.