Hi Miro -
Thanks for your message. I'm the product manager for Synthetic and Real User Monitoring here at Elastic. I'm glad to see you're looking into what we can offer! In terms of multiple geo-locations, Heartbeat can be installed and run from multiple geo locations that send data back to your main Elastic Cluster. As Heartbeat is so lightweight, all you need is a micro instance from any cloud provider and you'll be set. There's some fields in the Heartbeat YML for you to name the location that it's being run from and the Uptime interface will show you the Monitor results from all of the available geos.
In terms of a hosted synthetic monitoring service, where we provide the testing nodes and agents, this is a new capability we're adding as we speak. I can't communicate any public release dates but hosted heartbeat pings is an extremely high priority for us and is under active development.
In the meantime, if it is possible to set up those mice instances to run Heartbeat from globally, you'll find it a fantastic solution with resource-based pricing vs per test run pricing.
I hope that clears things up. Let me know if you have any more questions and I'll be happy to help out.
Drew