I think Hiten Shah, CEO of KISSmetrics, is too distracted with recent lawsuits to understand the mistake his company made: not looking out for their customers.
Legality of using ETag for tracking or reusing same ETag hash across domains is unclear and should be answered through legal process. What is clear, however, is that their usage raises suspicions and invites accusations against their loyal customers, not just KISSmetrics.
KISSmetrics should have foreseen this but apparently either did not or did but failed to act before it blew up. I hope my two cents worth will help them learn and improve their service. Lawsuits may come and go but lessons learned will stay with you.
An ounce of foresight is worth a pound of hindsight.
Excuses make poor stain removers.