James, Dell's RAID 10 info sounds confused to me. Actually, it reads as if it was written by a secretary after taking notes on something she didn't actually understand.
From the above it is not really clear just what the hell their "RAID Level 1-Concatenated" is, but they presumably mean that it is atually RAID 10 done in 1,0 fashion, which would be good.
But their info above is all confused, they are mixing together discussion of hardware and software RAID without ever explicitly saying so, the whole sentence about "In a concatenation ... the entire volume becomes unavailable." is misleading and only partially accurate, etc.