I wrote my own CMS/framework which I started about 8-9 years ago, so I use that. In my main business I sell a "pro" version of it as well as customization/hosting/etc, and naturally it's also the framework I use for my startup too. For those that are interested:
It's in PHP 4/5, GPL licensed, decently clean code (in 8 years there's obviously some cruft at this point :), but also has a few nice things built-in like a full CMS on top of it, multilingual support, a couple dozen modules that save some time, ORM library, and the ability to setup A/B tests just by editing a page, which is starting to come in handy these days.
Some challenges of rolling your own are that you have to write the documentation, and provide support/training/whatever else since developers aren't likely to be familiar with it (unless it's open and gains popularity). Some things to consider when weighing your options... :)
http://www.sitellite.org/
It's in PHP 4/5, GPL licensed, decently clean code (in 8 years there's obviously some cruft at this point :), but also has a few nice things built-in like a full CMS on top of it, multilingual support, a couple dozen modules that save some time, ORM library, and the ability to setup A/B tests just by editing a page, which is starting to come in handy these days.
Some challenges of rolling your own are that you have to write the documentation, and provide support/training/whatever else since developers aren't likely to be familiar with it (unless it's open and gains popularity). Some things to consider when weighing your options... :)