Looks awesome! I am still waiting to find somebody to play it, tough I must say I am aiming for 1/300 since that way I can use dnd monster miniatures and the like.
Your approach is much cooler, and I must say that way individual body part damage makes a lot more sense. Did you have some monster on monster combat or only monster vs army? I really like the way some failed attacks can lead to counter attacks in these rules.