I've used the cheat code to max it, and yea, it's 13 hearts. Been playing this game almost daily for 9+ to 10+ months now (depending on weither you count v.1 or not) and 9 IS a very good score. Best i've ever gotten without cheating was 10, and I only did it once.
The real shockers, the best games as it were, are when you have exactly 3 hearts left and there is exactly one bricks left, skin of the teeth, so satisfying