How much time do you or your group spend managing the clients expectation apposed to actual testing?

I bring this up because it loosely relates to the Geographical location of load generators discussion.

I know in my group we spend almost as much time managing the clients expectation on performance as we do in testing the application. I find this is often due to the sales people or system delivery managers not understanding all of the intricacies of software and system performance.

While we often have contracts that have SLAs (Service Level Agreements) attached to them at times we find it hard to show the client we have met those expectations.

I have been involved in applications that have met the SLA in the lab but it has trouble meeting the SLA from the client location thus the client management role.

So do you do client management?

If you do client management do you have direct contact with the client?

How do you manage the clients expectation?