[vacri]

There is an existing baseline before Slack was released that you can take as a rough baseline.

It's true though - Hipchat was caught napping. Atlassian backburner'd it at exactly the wrong time, and by the time they starting fixing things, it was too late.

This being said, Atlassian isn't really a 'startup' anymore. Hipchat is a side-product of a suite of gorilla products.