I have been using Hitachi VSP G700 for the last 5 years now. I have never experienced any performance degradation or outage. Also, no disk failure detected till date. It has separate HNAS controllers as well as HNAS management tool which makes it difficult to manage NAS and SAN from multiple management tool, not a single platform to manage both NAS and SAN. For universal Data replication from DC to DR site, it needs to be configured with separate journal pool at both sites which is a challenge sometimes.