I can reply on the TIP issue with a 964, here' s my tuppence worth.
I faced this question myself when entering the 911 market last year. Of the C2s I saw, the best body and engine were on a Guards Red TIP, 2 items I did not want. I have always driven manual and preferred to control the gearbox myself.
However I have been happy with the TIP so far. I have never found it stalling power due to too high a gear. For overtaking, the kickdown or the manual change down have always sufficed. On hindsight I wonder what my fears were in the first place. I expected wrong gear selections which have not appeared, but then there are 5 auto modes, not just Sport or Economy, and it does not change up when cornering.
Certainly the OBC supplied with TIPs is useful for my age car: for the next generation 993' s I would hope they all had OBCs.