Me and my lad both have 2 sets each. We do practice and one race on the first set, next two races on the next set and so on. They're 5000mAh and I generally only put back in around 2600-2900mAh.
Mine are 100C and his are 30C - never noticed a difference when using his in mine (7.5T in a 4WD) as basic maths states that 30C x 5A = 150A (constant - 60C burst) = 300A) which is what my ESC is rated to anyway.
