Going a bit off-topic here but open source is partly a cultural test. There are great programmers who are 9-5 and there are terrible enthusiasts, but involvement does mean that people are going to be speaking the same language to a large extent - and the biggest overhead in delivery teams is usually communication.
In fairness, there are a lot of great programmers who work on projects they really believe in and spend all of their available free time dedicated to them. Even if they're for the company/enterprise/startup they work for.
