I wish that there was an equivalent of the Ross-Tech VCDS (for VW/Audi, aka VAG-Com) for Porsche. That tool is awesome, and doesn't limit how many cars it can be used on - plus there's more functionality and ability to do a wide variety of coding changes. Alas.
I also have a genuine Durametric, though, and it's already paid for itself on my Boxster and my parents' Porsches.