We are using Simple SEO Urls and have the category depth set to 1, all of our cats and subcats have a nice clean url with only 1 level deep.

However, with the introduction of our product collections, we were thinking it would be more advantageous to show the collection name in the url like this:
http://www.mysite.com/elite-collection/premium-tshirts

rather than this:
http://www.mysite.com/premium-tshirts

My question is this, do you think personally think it's OK leave the collection name omitted like in the second URL, or do you think we should set the category depth to 2 levels? Changing to 2 levels would make all of our existing categories (not product collections) have much longer urls which seem redundant, not to mention the amount of redirects we would have to put in place.

Alternatively, do you know if there's another way create a 2 category depth JUST for our product collections, and leave the existing categories at 1 level?