SCSI just works, on everything I've ever used it. I've had a
occaisonal problems with things like termination. High quality
cables and enclosures solve this. I wouldn't let an IDE disk get within
thinking distance of machine whose reliability I cared about.
Cabling... most of troubles caused by cables for me - it is
reason I do not believe external devices.
Eh, that's something unusual. Unless you buy cheap bad cables or
try to solder them by yourself.
No, good cable in bad place - after touch time to time
some external cables change its state.