Several years on from when this post was first created I have used several free templates for various projects. In the end I always ended up splashing out $50+ for a premium theme with additional features, continued support and security updates.
Registering the theme with a product key allows easy one click install updates saving time and effort with uploading files by ftp. It's always advised to backup first.
Some theme developers offer an extended theme license meaning you can install a purchased theme on several websites/domains and register it with the same product reg key and avail of one the click updates on all websites for a one off fee. An extended license can cost as much as $2950, but if you find a good theme with lots of layouts and features you can use it in most (if not all) projects leading to less time spent researching new 'freemium' themes and plugins for each new project you start.
Advantages:
- Regular patches and bug fixes
- Regular security updates
- Extended features and functionality
- Access to premium plugins and updates
- Up to 6 months support
- Access to community forums