tedster - 7:40 pm on Dec 4, 2011 (gmt 0)
I'd say yes, brevity is better - but mostly because of user behavior rather than any direct metric that looks at the URL.
The choice of dashes or slashes is, as you say, merely cosmetic. With URL rewriting within reach for almost any website, it wouldn't make much sense to weight rankings very heavily on factors that are so easy to manipulate - merely cosmetic, as you say.
The purpose of anything cosmetic is to appear attractive to people - and longer URLs don't have as much appeal.