Bovenstaande quote klopt. Vanaf model 2002 heeft de 996 de bak van de turbo, en heet tiptr S. Deze is zelflerend, sterker gebouwd, en iets sneller.
Met de stuurbediening heeft het niets te maken.

Year differences between tiptronics
All the tips until 2001 are basically the same on a 996. The 2002 model saw Porsche use the Turbo tiptronic unit instead of the older one. This gives 2002 cars a 'stronger' tiptronic and some other features.

Manual shift in D
When in D, you can still use the buttons to manually shift. It returns to D after 8 seconds in a gear.

Stationary overrev protection
You will not be able to rev the car while it's stationary beyond 4k RPMs. Don't do this anyway or you'll be buying a new torque convertor (2k installed).

More shift patterns in D
It has 250 shift patterns instead of the 5 or so on the older box. This means it can be cleverer in D.

More robust tranny
The 2002 onwards has a transmission from a much more powerful car, the Turbo. So, I'd imagine in a normal 996 that it will last longer than a pre 2002 transmission would.