Don't get too hung up on the word "enterprise" it's a very misleading and damaging label for CMS (and software in general). Like Jake said, figure out your requirements, goals, and what your future looks like. Then you'll be better able to make a decision about building something custom vs. grabbing something from the shelf.
Open source is great and I would highly recommend leveraging it...But there's nothing that says you can't use an open source framework to build your custom CMS solution. In fact, this is exactly what happens with the larger projects I've worked on over the past 10 years. They ALWAYS move to a custom solution when they outgrow the open source CMS. This is simply because there is no such thing as a one size fits all CMS. You gotta go up a level in your strategy there to the "framework" level that is less pointed and more flexible.
Again though it's going to depend on your requirements...But honestly, if you're building a more robust business/app/product around this codebase. DO NOT reach for a canned CMS. It will end horribly for you. If it's a simple company blog and will always remain so, have at it. Go wild on your WordPresses and Drupals and Al Frescos of the world.