The yellow flashes are an excellent addition, Steve; a very nice touch.

To the OP's question; some people will tell you that if it has a silver cantle, it's evening wear and if it doesn't (and doesn't have a head attached), it's day wear. I think you'll find most people aren't this hard-nosed about it.

I have no problem with folks wearing leather sporrans with silver cantles with a tweed jacket, with a black argyll, or to most black-tie events. The silver cantle would look a bit out of place with a "casual" outfit with no tie or jacket, and the leather bag wouldn't cut it at a truly formal event (a very nice black- or white-tie affair). Aside from those two situations, I say go right ahead and wear it!