[schrijver]

Well since they are former competitors that shouldnt really matter to you, should it?

In a business sense, open sourcing it can allow you to gain recognition, visibility and goodwill.

In a personal sense it could offer fulfilment, and in a moral sense, like you say, you are giving back to the community.

However, be prepared to spend some time in cleaning commenting and documenting if you really want it to be of use to others..