Hey, it's Matt here to answer this question. Our differentiations compared to Metronome are twofold.
First, we actually, and literally, measure and collect the usage (whereas they don't). So in Metronome's case, a SaaS company needs to develop an internal system to measure the usage amount, and be responsible for sending the measured amount to their REST API or via Segment. However, based on our own experience and many others', those work actually represent the majority of the challenges and engineering time for usage-based billing. Therefore, Paigo takes the full ownership to literally measure the usage whenever we can, and pull the data into our backend journey. So there is no development or integration needed.
Secondly, Metronome has a sole focus on billing infrastructure, whereas we are a broader footprint on usage-based business model. We not only provide billing infrastructure, but also pricing toolkit to optimize unit price based usage, and business analytics such as MRR/ARR/retention for usage-based model.
Hope it helps. Happy to dive deep in however way you are interested!