It's a large system with extra-ordinarily tight performance requirements, and a lot of integration with external systems, and by nature hard to phase in gradually. That kind of system is very hard to get right first time regardless of your toolset. I'd be interested to hear more about thier methods to deal with these requirements and risks, less about thier platform choice. IIRC, both this and the previous failed system were outsourced, which doesn't exactly fill me with confidence.