it works great with the 13 pro max! this is my first gimbal and ive only had it for a week and i am having a lot of fun.
i actually bought the 3 at first to save some money, but i just didnt like how it has to exactly be balanced. so i returned it for the 5 as it doesnt require balancing. the magnetic clamp is amazing, just clamp it on and it stays securely tight on the gimbal. i never have the worries of dropping my caseless iPhone!
i am definitely keeping it, it is really inspiring to have. makes me want to play and use the camera more. hope that helps and good luck!