It's not a 'truth', just an observation - We had a fair no. of people posting about problems with their 716SA's early on - The general problem was pretty much down to chipset compatibilities vs the drives bridge chips (AFAIK, the 716SA is actually a 716A with a SATA bridge chip in it!).
We had a bunch of people brick their drives when they flashed them because of this, and it's mainly that observation that sparked my comment. The part about non-hard disk SATA drives not being as mature as plain old ATA is probably a 'truth' 'tho.
SATA is still bleeding-edge tech, and I occasionally trip over some weird problem with it now and again. Heck, a few weeks ago we found that 2nd gen SATA HD was constantly corrupting data, and ended up having to upgrade the motherboard's SATA drivers and flash the hard-disk firmware!
I currently recommend ATA for reliability and SATA for speed (For instance, my SATA drive is only for games and video editing stuff; I still use my ATA's for everything else. The performance difference is non-existant anyway!)
I just wish SCSI was cheaper!! The damned controllers still haven't BUDGED in price!
Mmm.... 300GB SCSI Ultra320 hard disk... cost more than most of my machine...! (Â£600!!!)