I like the narrower apron because there is no sporran to push it down. Even when not wearing a sporran with my Stillwater Economy, it doesn't drop between my legs on its own when sitting.

With the much stiffer fabric on my new denim utilikilt (blog review coming soon), I can not imagine that it would drop between my legs if it were wider. Actually, the new denim is so very stiff it might not even stay down when pushed into place of it weren't narrower than on a traditional kilt.