I see they sell two versions. A "normal" size one and one that is 2" longer. Is one preferable to the other? What's the extra length for?

Thanks in advance for any help you can provide.

It's hopefully to prevent a problem where long-term repeated movement of the hard disk's shock-mount tray causes the IDE header to be pulled off of the motherboard.

Essentially, it's to help prevent a repetitive stress injury.

The problem is simply cured by increasing the MB to primary connector distance.