Glad you like it! Completely agree about the overkill-ness of ELK.
I haven't had a chance to try Datadog yet but it looks great, the one complaint I've had with Splunk (or at least the way we use it at work) is that it's still "Just logs" and sometimes you need more than that to investigate issues while Datadog seems to cover more areas of monitoring in one package.
Datadog is really great for this but can be expensive