Leather Hunting Sporrans

[Spc. Scott]

That one looks pretty formal to me. Admittedly I don't have a lot of knowledge about what differences there may be between the types of sporrans but I know that one looks really nice.

[Kiltman]

The "tradition" is that sporrans are informal, semiformal and formal. As far as I can tell to be semiformal or formal it must be a fur sporran. To be formal it generally has a cantle, etc. So, it's not a question of leather or not. I suggest if it looks good it is good.
A hunting sporran generally opens at the top with no flap that goes over the front as in the Rob Roy and many cookie cutter sporrans.
There a many web sites that will explain all of this. Also see Charles Thompson's So You're going to wear the Kilt.