Yeah, we totally understand the upgrade concern. The short answer about upgrading is you really don't have to, since Foundation isn't like wordpress or Drupal where there are security implications. ZURB has about 30 properties around the web and some are running on Foundation 5, 3, 2 and even pre-releases on 1. If we think the property will benefit we'll upgrade we will if not we won't.

The main benefits here are to file size, customizability and navigation patterns. We're doing a client upgrade now because they wanted to benefit from some of the additional Sass grid tools and then eventually be in a place where they could swap to the Flex grid and shrink file size even more.

Overall we'll upgrade some sites, but not all.

Hope that helps :)

Great question. I'll try and have some of the Foundation team hop on this, but a few things stand out to me:

• The CSS is over 50% lighter than v5
• New Flexbox grid
• Motion UI Sass animation library
• The Yeti Launch desktop app makes it super simple to spin up a new project
• Each component has been re-coded for Accessibility standards and includes instructions on how and why to use them to meet accessibility standards.

There are loads of other improvements, but those really stand out in my mind.