Hi HTsoon,
I agree with the strategy to use 500 in midscalp and 1000 in the crown. You can use beard hair to add more overall density down the line instead of using it exclusively on one area. Since u already cut ur back and sides short, the scalp and beard hairs should be indistinguishable in the lower crown area if u choose to transplant beard hair in the crown in the future.
You mentioned you have favorable donor characteristics. Can you throw some light on it? Do you happen to know your hair thickness, graft density, percent of miniaturization, etc???
Also, I recall you were thinking a while back about transplanting scalp hair as much as possible and use beard hair to repair the donor area. Did you consult with your doctor whether this is a possibility?