Costs of forking

A lot of full time Drupal/CS consultants I've been talking to here in Vancouver have been sharing concerns about how to meet the needs of their clients while still being able to contribute code they development back to the Drupal community. The general assumption is that most clients are oblivious to the mechanics of open-source communities and assume that they are paying simply for an engineer to develop new functionality and ignore all the time required to work with the Drupal community to make sure contributions and patches are accepted and merged back.

I think the simplest solution is to figure out a way to asses costs to forking code that can be communicated to customers upfront when contracts are negotiated.

How about this estimate?

  1. Costs to mantain your own forked module: 25 developer hours X $100 an hour X 2 times a year = $5,000 a year per module.
  2. Open-Source development resources lost: 5 hours per patch X $100 an hour = $500 per patch.

Using these estimates I would think that consultants should be able to justify adding in a line item to their contracts up front to cover their costs to contribute their code back to the community. Do you think this will work?