The head hackle you have pointed out yourself and the tag being a little too far round the bend has also been pointed out (Something I am prone too). The hackling looks technically good to me, but I lean towards much lighter hackling for Snatchers - This however is a matter of taste. You might want to try a few with the leading edge of the hackle stripped of fibres (I don't think you have done this).
I don't mind the JC being on the outside, but I would go for one a little shorter, that still shows a little of the black at the tie in point.
Definately a fly heading in the right direction.