2x 2TB WD green in ReadyNAS Duo?

While I cannot offer any opinion on the LCC and wdidle3 (I do not use WD drives in my NAS units), keep in mind, any drive can and will fail, usually at the most inconvenient time. A give drive may fail early, while it's neighbor in the NAS may run for years. When I first installed my NV+ almost 4 1/2 years ago, I installed 2x500GB Seagate drives. Within a month, one was dead. When I pulled it out it was cold to the touch. I replaced it with another of the same model and the unit resynched. I then ran the unit for almost 3 years, slowing adding more drives (different manufacturers and sizes). When I upgraded the drives to 1TB, the one remaining original drive had over 25,000 hours on it, and the replacement for the one failed drive almost as much. Seagate replaced the failed drive.

A year and a half ago, I installed two NVX units, each with 4x1TB Seagate drives (4 pulled from the NV+) and 2 spares purchased at the same time. Out of the 10 drives, in the year following, I have lost two more, both of which have been replaced by Seagate.

If you are having write errors, I don't think that is related to the LCC. While one can purchase Enterprise class drives which will reduce the chance of failure, it will not eliminate it althogether. After all you have electrical circuitry on a drive and mechanical movements within a drive. Either can wear and fail. This is why one should never trust their data to a single device, even if the device is an NAS with redundancy. After all, the failure could occur within the NAS, or one could encounter a catastrophic loss of the unit itself. If one reads through the entire manual, they will be reminded that the NAS is not a backup plan.