Some of my clients are subject to public disclosure rules -- mainly, they can be audited by government authorities at any time. My company would be completely off the radar screen because I am way too small for a government auditor to care about, but in these cases I try to be consistent in my dealings with the clients. I would probably be consistent anyway WITHOUT the audit issue, since the work I do for these clients is generally similar and would generally similar and subject to the same competitive pressure in my industry.
My hat is off to you for threading the needle so finely. I hope you can maintain if you provide a just service.