Not the OP, but we went with Icinga2. Aside from some crappy pre- and post-upgrade scripts, it works remarkably well, and is compatible with the Nagios monitoring plugin ecosystem.
Add in some Skyline (based off the Etsy project), graphite, and collectd, and it makes for a flexible and extensible monitoring solution.
Add in some Skyline (based off the Etsy project), graphite, and collectd, and it makes for a flexible and extensible monitoring solution.