There are more reasons to consider the platter HDD approach to have a longer lifespan than just track size. Cabling, controllers, and even internal array structures. The problem with SSDs is that miniaturizing flash memory itself is limited by design. Both HDD and SSDs have temperature limitations. SSDs actually use more power than HDDs (an OCZ Agility 3 SSD uses 1.5W at idle and 2.7W under load, whereas a 1TB WD Scorpio Blue HDD uses only 1.4W under load and a mere 0.6W at idle!). Even if you look at the most economical SSD available it will still use more power than an HDD of any size. I realize that most people look at the speed of the SSD and think that's all they need to know. Well, except if some of the early hybrid projects hit the market the HDD will literally leave the SSD in the dust! Even if that doesn't happen, would you really want a 4TB drive, when for the same price you can buy a 100 TB HDD? a 1 PB HDD? That day is coming.