We've seen a high failure rate on SSD compared to SAS & SATA drives. All of our servers are in a RAID environment, so a single failure does not take the system offline. Additionally our backups and snapshots provide another level of redundancy against disk failure. So far no data loss.

That lines up with our lease structure for hardware which is 36mo.

It also lines up with the continuing improvements in server density which compensates for the increased costs in power usage and rack space so it just encourages good behavior in rotating out older hardware.