I'm a huge advocate for free ('free' as in Perl), but also work on commercial software at work.

Instead of having the code half/half license, another option may be to open source (ie. CPAN) the code, and then sell integration/deployment/support services.

That way, you provide yourself/crew with an income, while reaping the potential benefits of having users of your code provide you with patches, PRs etc

I mean, if it's open source, on a services engagement, you can learn about how your software is being deployed and used, and if the client can code, you could help them (another service: custom coding), then request you add their code back to the base product.