Welcome to the Q&A Forum

Without server configuration, I'll take a stab at this.  I see only one potentially significant issue: Inbound links.  When someone links to the website, do you want to count on them linking  www.site.com instead of www.site.com/catalog  ?    Shorter URLs are easier to remember and they can improve the direct type-in traffic. For navigational purposes, your server can resolve to the site homepage when the incomplete URL is entered into the browser, but a 301 redirect doesn't carry over all of the PR. Less significant is the superfluous term in your URL.  Legend has it that shorter, simpler, more relevant keywords in your meta-data and URLs is the way to go.  Will a single additional term drop you in the SERP?  Highly unlikely.  Most ecommerce sites have to use a similar format. If you don't have reasons of necessity, go with the short URL.  301 redirects (URL iterations 2,3,4,etc to a single URL format) should suffice for those site that have been live for some time.