What is the nature of the content that you wish to contribute? And what sort of website is it going to be uploaded to?
When I want a fairly simple off-the-shelf CMS (content management system for those at the back not paying attention!) I provide Joomla. It's open source, secure, easy to use from both parties' viewpoints, and usually up to the job. I have used a custom CMS (from a specialist developer) for a very complex project, but Joomla can do a lot for you.
It will help you if you read about it first before deciding. click here The most obvious pro is a reduction in ongoing costs for regularly updated sites. Then there is flexibility of self-reliance and quicker timescales. Get your developer to show you Joomla at work from the client's perspective: if it works for you and for your project, take it up.