Damn. As a founder in the incident management space (Rootly) I've had a lot of respect for Opsgenie. They had unique features like heartbeats and ran a lean but mighty team before selling to Atlassian. We saw them the most in Europe by far.
Okay here comes to promotional part (don't hate me). If anyone is looking for a modern alternative to Opsgenie that isn't as expensive as PagerDuty, Rootly is worth checking out (Slack-native, holiday scheduling, request coverage, clean mobile app, etc).
Previous to Rootly I worked at Instacart where I helped us transition from PD to Opsgenie. Afterwards, still not being happy I built Rootly.
Today, we've helped Trivago, Motive, Yahoo, and quite a few others make the switch. Pretty easy with our importer tool, etc.