How do you know the fuel cut/limiter doesn't kick in at the redline in the cars I've been in then? I'm also thinking that those things are all functions of the transmission (which will force an upshift) rather than a physical feature of the transmission in modern automatics- but that's just speculation.
You drive manual, so yes I am inclined to think you'll know what you're talking about when it comes to manual cars and gear changes, but we're talking tiptronics here- something which I've had quite a bit of experience with both in the driver's seat and moreso in the passenger. Sure we don't have any Ferraris (any more) like Top Gear (for the record; we had a F355 in Manual) but I'm saying that in MY experience, when I've seen my cousins race, I've never seen the tacho go past where the redline starts when in tiptronic. Apart from the CL55 (which wasn't driven in tiptronic mode), the 740iL, the 750iL, the S500, 540i, 645i, 328i and 330Ci all forced an upshift just as it hits the redline from what I've seen; and unlike you who is basing your knowledge on what you've seen on TV, mine is based on real life experience- sure I wasn't driving, but it sure beats what you can see on TV footage which has been spliced/edited. I will confirm with my cousins regarding the GReddy 350z tiptronic.
No matter how techy your knowledge may be, my post is something which I've said I noticed from my own observations- unless you've driven the exact cars, I don't see how you can claim to know whether or not the tiptronic systems force upshifts or not. Even the Mini Cooper (I've heard) forces upshifts in the tiptronic mode; however some cars out there do not... but like I said again, these are my own observations with cars which our family owns.
Btw the ECU mod which raises fuel efficiency... that's a new one. All the cars in Malaysia that are owned by my family have had ECU modifications performed- and fuel efficiency never increases. The stupid meter which tells you how much fuel you're using at any time is nearly always dangling at 40L/100km.