I've been building web-applications for a super long time for a wide-range of customers, you don't want to get bogged down with building something, you'll have issues.

You're main goal should be focused on creating great content and working on relationships to build readership.

There is no point in creating a massive headache for yourself.

You say, "We're launching a news/media website". That means you don't know if its going to work. My opionion these days: I think SquareSpace is 'sexier'. It's going to look sexy out-of-the-box with very little modifications and a monkey can edit the site since it's so easy. Save yourself a headache and go with SquareSpace, please.