Not sure I agree with your last statement there serial, but whatever ... I know that Sydney Mint sovereigns command a healthy premium over spot, due to their age and rarity in any grade > F.
And having just checked my copy of McDonalds price guide I can see why OP might be concerned as to how much impact a ding might have on a coins value (if we are talking difference between the coin being graded in VF or XF).
But given that Sydney Mint Type II 1864 Half Sovereign in VF grade was valued at >$2000 (2013), even if its realistic sale value was only half that, I would have thought that getting it slabbed and graded would have been a very worthwhile exercise regardless of the minor rim dents, not only to get the coin graded, but to protect it from any further damage.