That is why I said may actually reduce performance.

With a RAID array the parts of a large file are still hopefully stored in reasonable proximity across however many disks they are spread across. If the 50Gb file is spread across 5 disks then when it was written ideally the heads on each of the five disks would have been able to put their (10Gb+parity data) down in one long stripe. Admittedly if the head has to seek from one end to the other now it has a little more than 1/5th of the previous distance but there is still a good chance of a bonus for sequential read.

Even NAS still has spinning platters and inertialy challenged heads at the coal face.

Cheers,
R.