Charta started off as a Joomla website, and the client was keen to have the same freedom to manage the website but didn't want to use such an old fashioned CMS anymore. Enter SilverStripe!
Every page was redesigned and the CMS was built in SilverStripe 3 and branded to match the public facing website.
All the functionality from the old CMS was copied across and custom modules were built to allow the client to continue doing what they do, but now with ease, and with more flexibility.
When a new function is required, the SilverStripe framework (and/or Sapphire) makes it easy to add or create what is required.