I think you may have overlooked an important part of the WD package. The drive carries a 2-year warranty and customers should know that it is not as easy as that. This week, I could not back up my MAC on the drive. The entire week of shuttling between WD and retailer simply led to one conclusion: WD's guarantee doesn't function.
1. I contacted Mac, who determined that it was not Time Machine but that the drive that was at fault. Told me to check with WD. Also to have drive and cable tested on another computer. 2. Went to retailer to do all that. 3. Retailer said it could be a compatibility issue since WD has special drives for Macs. Meaning, WD's retailer shouldn't have sold me the drive in the first place. OK. Retailer's idiocy. 3. Said to have drive replaced. Contacted WD, who said they could replace drive, but I had to send it in, and all data would be lost. 5. Very politely gave me contacts for data recovery, which was quoted at $3-500. So, in fact, the malfunctioning drive could not be replaced, not without me spending recovery cost. Yes, WD does offer courier service, but guess what? This is another $50 or thereabouts. Either way, it means that you really have a guarantee for a return of a product that really cannot be returned.