I'd days ignore the errors. If the disk starts with reallocating blocks, that is a reason to keep a close eye on it, if the counter rises, that's a cause for concern.
The load/unload is annoying, but I don't think we ever had a disk fail to that (and we sold lots of them), in genereal, the WD Green were a solid choice. However, they were not great performance-wise, the load/unload often brought performance down, unsuitable for server applications. OK as a backup drive (this is how most of our customers used them).