Re: swimming against the tide
Nothing wrong with swimming against the tide if the tide is going out.
In the short run, Slack does seem to be getting lots of attention, but I wonder how much of that is VC-driven. It is pitched explicitly as an email replacement by people who would clearly profit if we all stopped using email and started using Slack. Frankly I can't see the point, since email is a better interface for the sort of communication I do, but I'm aware that others like to work differently.
In the long run, Slack will survive if the people who use Slack actually *are* more productive than those who don't.