Fwiw, I lead Product for Ocean at SpotInst. Your analysis is _spot_ on :). At SpotInst, we predict interruptions by calculating a Spot Market Score which is based on Instance Family, Type and AZ (using historic data). This allows us to spread pods/workloads across a variety of spot instance types while delivering an SLA. As an additional data point, we have a mix of stateless/stateful workloads running 24x7 on our platform. For critical/management workloads/apps, RI could make a lot of sense and we can dynamically buy/sell those on your behalf, delivering a fully-managed Spot <--> RI <--> OD solution where needed.