Just a point on the speed thing....it really depends what you are comparing. 1x SSD vs 1x HDD, yes the SSD wins the speed contest hands down.
However, in my environment I have SSDs where I get ~500-550MBs sequential performance. I also have a RAID array of HDDs, that cost less than one of those SSD (significantly less), delivers 500-550MBs sequential as well, but also has data redundancy.
The power debate is also somewhat moot - all my HDD systems power down the HDDs when not in use. That makes them very power efficient. As they are storing data that is accessed rarely that is *most* of the time....but when it is accessed it requires fast sequential access...which a RAID group of HDDs gives in spades.
Biting the hand that feeds IT
