I'm a bit of a graybeard, so please bear with me if I'm asking a stupid question. Back when 10K SCSI drives came out, I had (still have) a MegaRAID controller. One of the first lessons that I learned was that if there was an error on either drive in RAID 0, everything was toast. So, I quickly bought a third Cheetah and went to RAID 5. Now most good MBs have RAID 0 or 1 on the MB. Since RAID 0 is striping and is NOT redundant, it's a bit of an oxymoron. Your review bypassed RAID 5 and went to RAID 10.
1) Is RAID 10 striping two pairs of mirrored drives or mirroring two pairs of striped drives? Just curious on this one. I don't think it would make a lot of difference.
2) Have prices changed so much that four spindles in RAID 10 makes more economic sense than three spindles in RAID 5? Mathematically, it's hard to believe that argument would scale, since it would require 10 spindles in RAID 10 to duplicate a six spindle RAID 5 array's capacity.
As I said, I've been away from the RAID game for a while, so I really don't know the current basics. It seems to fly in the face of what I learned before, but that's not that unusual, as hardware evolves (this from a guy who punched cards to program an IBM 360 in Fortran IV, in high school in 1969).