Also, the problem I think we all have with Slack is picking the important messages out of the deluge. I've been mulling a sort of SLA/prioritization tool for Slack messages. Something where you could set SLAs like "If my skip level manager DMs me I want to respond in 5 minutes" and do the Pagertree sort of escalation until I respond.

You can apply this to channels and do more intelligent notifications than Slack does. Like if a Director or higher posts in your team's public channel then kick off the Pagertree notification. Or if a post has gotten 10+ replies in 5 minutes.

Can't tell you how many times I've been late on important messages because Slack's notifications are coarse and terrible.