since i own a 500 i can chime in here. the 500's tranny does soemties seem to shift a bit much, but its been way overrated in road tests. the time that it hunts the most is in town at mid range speeds when you are on and off the gas a lot. on steeper hills it shifts a lot too, until you keep your gas steady and it finds the right gear then it holds like a bulldog. the tranny actually holds and keeps gears better than my old 99 SHO, however. my SHO used to short shift a lot. the 500 does stay pretty decisive about what gear its in as long you are not fking with the gas pedal. if you punch the pedal hard, it picks a gear and sticks with it and doesn't shift that much once at cruising speed. on the interstate at high speeds, it stays firmly planted in 6th or whatever and loafs along merrily at 1700-2200 rpm, depending on how fast you are going. 78 mph is like 2200 rpm i think, and it will accelerate easily up from that or kick down quite fast and find a great passing gear with some good snap. the first trip i took with the car over t'giving my last leg i got 26 mpg and that was with plenty of stopped in the ice storm interstate traffic. once it breaks in, i should see close to 30 on a good trip.
Sometimes I wish it would shift quicker, but I am made aware that there is a TSB out now on getting a tranny flash to improve the shifting...i might get that done. Shifts themselves are not 100% smooth, but still way better than almost any older Ford and not jerky or anything like that.
The big culprit is the lack of low end torque and power in the engine, and the powertrain buzziness at low speeds and taking off from a start. If the engine had more gusto, then no one would need to make any comments about the tranny. The tranny is simply doing its job with an underspecced engine. Its almost never that it picks a wrong gear, actually and it must be adaptive because since about 1500 miles, its been holding gears longer, too.
And even though it feels slow off the line, overall the car feels quick. above 30 mph the wholecar comes alive and has good kick down and that's when having the 6 speed really makes it shine. Any car that cracks 8 seconds is doing good. the thing revs great and never feels winded like the 3400 in my aztek does. i mean, there's NO comparison. the 3400 is more sedate in town and feels better from a stop but is quite breathless and busy on the highway in upper speeds.
The Duratec 35 or Yamaha v8 will solve those issues when they and the new 6 speed hit market in 12 to 18 months. the 3.0 duratec will be fine as a base model engine.
bottom line, the 6 speed is very useful, enhances the function of the car, and the overdrive gears help it get great mpg. Anything beyond 6 speeds wuld be useless IMHO, but Ford and GM will benefit greatly from their jointly developed 6 speed.
i bet the 6 speed teamed with the 3.6vvt will be a great combo in the Aura and other GM cars if the tight ass beanounters let them put it in. The Impala SS alone would benefit tremendously. i didn't much care for the 4 speed in the SS when i drove it. the 6 speed teamed to that small block or even the north star will be a great combo.