Two things I wonder about this:
1) The "no code changes" part implies it's adding another layer of code somewhere, which means another thing to trust and probably not be able to audit, which is not automatically OK outside the "move fast break things" world. Am I misreading it?
2) How can you add metrics with "no overhead?" Surely there must be some overhead... and then it would be nice to be able to measure how much.
For me personally, #1 is a real issue and #2 is just hypothetical, but I would expect it to be the other way around for a fast-growing startup.