Thanks, theunartist. However, the changing the order wasn't exactly what I was trying to achieve.
I wanted to be able to stop folks from being able to click "older posts" to see my back dated stuff that might not fit with what I'm trying to show them on the front page. Basically, I'd like to have 9 images curated for the front featured items, and then anything that falls into a different category only be accessible via the menus.
So, it might be a neat/usefull feature if you were able to limit your front page to only display a certain category. In the mean time, though, I did just find a bit of a work around for anyone who is interested.
In the content-portfolio.php file, there is a line with this code towards the end:
<?php portfoliopress_content_nav(); ?>
if you delete that, it will remove the "older posts" link from the portfolio pages. Which means, I can back date my stuff like you suggested, and anything over 9 won't show. Then I can just categorize those posts and make them accessible through my menu. Done deal. Which is perfect since I don't really want to have more than 9 pieces in any given portfolio category anyway!
I was a little worried that it might remove the "older posts" link from the blog archives... but it did not!