This is the argument that drives me bonkers about wanting to 'hide your source'. You as the code developer know the code. You know the strengths and limitations, and having developed it are already hard at work at developing the next generation and have the reputation of being the leader. As the old addage goes 'Imitation is the most sincere form of flattery'. Additionally if your competitor is following you, then you have the strategic advantage and the competitor is doomed to follow. Let them eat your cake!.
-- It's the talent that has value NOT the code.