Savings varies by drive size. Easy to upgrade in the future to larger drives. Excellent way to backup or offload the internal drive for infrequently used files. Hot plug capability. Sensitive or private files can be locked away and not stored on the internal drive.
Portable drives cost more per GB than full size external firewire versions.
Completed drives have a 1 year warranty, the kit has only a 90-day warranty. See the update to the install page for how to check for sharp solder joints and component leads that could pierce the insulating sheet on the Firewire Direct circuit card. If the insulator was pierced, it could short against the hard drive can cause damage to the drive or firewire controller. Firewire Direct disk volume had to be dragged to trash to allow sleep on Powerbook. VST drive case cannot be opened to replace the drive without destroying the adhesive backed cover.