>Has anyone had the experience of a DBC changing content and length at the user site without modification by the developer nor user? Does VFP make any changes to the DBC as it's in use?

Don't know, but have had several corrupted DBCs.
My experiment with the readonly DBCs is still active, and seems to work well enough. There may be something wrong with it, but nothing bad yet...it might be worth a try if no updates are needed in DBC.