RC,
I have read this whole thread, and with all respect, you are all over the map in your considerations and rationalizations.
I am not an MD, but it obvious you have a fever... new car fever!
How can I be so sure?
Well, I do the same thing frequently, and am in the same process, spent the last week pondering and playing with options... CTTS or Panamera to replace my 05 CTT (even though my wife likes being high up and the 05 has an extended warranty to 2012 or 100K, currently at 35K). But it gets worse maybe a C4S instead( but I already have an RS (and a new one on order) and 997.2).
I bought a Black Series CLK 6.3 because I loved the growl...but Porsche came out with PDK and I had to have it, even though I am a 6 speed die hard. Proof..my F430 is a 6 speed. I loved the Black Series too but it was not a 911 (its only fault). I will eventually sell the F430 too, because I decided awhile ago to stay all Porsche.... easier for service and maintaining relationships, getting cars etc.. and the F458 while a technological marvel fails to excite me (too much like a Lambo!, or maybe it is the lack of Pirelli tires (j/k).. I went to Frankfurt to see it and the new RS color in the flesh!
Over many years I have gone back and forth with various marques but I always come back to Porsche (hence the above decision to go exclusive). Porsche simply represents the best all around automotive experience when all things are considered... at least it has worked out that way for me, but to each his own. Some might consider that myopic thinking, others might consider it evolved. Whatever works!
Reading through al the posts, I think you are going to finish up with a "debadged" Panamera! Provocative thoughts maybe, but insightful hopefully. I have spent countless hours on this and when you marry the driving experience with the space needs the Panamera presents a powerful argument..if the budget supports it... and it is no harder to park than a CTT. Plus, if I had the Autobahn to exercise it..well resistance it futile
Do not read this as a "know it all" post.
At worst, it is a poorly expressed opinion; and at best, it is a non critical observation which could be food for thought. Examples of cars owned are only provided to give weight to the extent of thinking and deliberation that I can empathize with (so no flames please).
You can rationalize anything!
For the fever, take two asprins, and have a nap!
The asprins won't do any good, but you might enjoy the nap (and dream about that Panamera).
Merry Christmas and Happy Holidays!