I saw this show as well, and although Patrick Norton is usually dead-on, this time he was off-base. He had read some stuffs in a mag, and mis-interpeted it. In theory, if you choose a huge block size (say 256KB) for your RAID, and all your data is in extremely small chunks, (say 1KB) your reads could take a hit. The odds are tho, even if you choose a block size that is not even close to optimal to the data that you store, you should still see some improvement in reads. Now writes...that's more complicated.
On the other hand, when Patrick answered that call, it was to some 9-year-old wannabe 1337 h4><0r, so its probally best that he told the kid not to do it, even if it was for the wrong reason. Don't want the kid wipin out the family PC cause he heard on TV it was OK to do so, ya know?