Hi Mike
In my opinion the sharper the leading edge, the better. My props have to be tightened up with protection otherwise the leading edge will slice straight through ones fingers. That flat section of the trailing edge of a surface drive prop should be kept that way. A sharp prop will give better speed and it will help prevent other handling issues. If you do attempt to balance the prop bear in mind that the face of the blades should not be touched, although I guess that is common sense. As you have a prop balancer (and I prefer the magnetic types like you have) it should be fairly easy for you to maximise the potential of the supplied prop with zero extra cost.
Cheers
Craig
Ken: Just on print size, I drafted in word and pasted the text into my reply.