Well, I haven't run into a problem yet, although my "rounded" cables are just bound (wrapped).
On a side note, I noticed that bound/wrapped scsi ribbon cables is definitely a no-no, as my Jaz drive wasn't recognized when I tried that. :-o
As far as SATA, I've heard that you can get equal, to improved transfer speeds on IDE drives on SATA ports by using an IDE to SATA adapter. I haven't tried it yet, but I'm looking to get some.