[EGreg]

Funny enough, we never seem to have such major problems.

Perhaps because we have a framework and documentation and a guide to get new hires up to speed. Also we have documented our practices, the tools we use, etc. And the new hires are instructed to do a project before joining the team. Once they have done the project they are familiar with a large part of the framework.

And as for those "business edge cases", new hires and all developers are personally given tasks by me, and we make sure to QA their work and code-review work by new hires.

So these are the main factors for why hiring new people has so far been relatively smooth. Still, let's not maintain any illusions -- new hires will need months to really get to the same place as existing developers.

But you don't have to have your own documented framework to do it. If you are using an open source framework and sticking closely to its principles, if you have documented your company's systems and made it clear what is expected of developers, hiring can be a great thing!