Allow me to contribute with my experience after owning a 355GTS F1 for 2 years (pictures in the garage section). On a side note, stay with the GTS concept, it's marvellous. Open air, full sound symphony, no soft top hassles. Driving the car with the top on (like a GTB) is a dull experience in comparison. Not sure why Ferrari gave up the concept.
Regarding the gearbox, the answer all depends on what you use the car for.
When driving, the box is really nice, smooth, dependable, and allows to focus all your attention on the steering. Upshifts are faster than you would achieve most of the time, downshifts while braking way quicker than a mortal can manage, unless you are king of heel and toe, and can keep the car straight (or even opposite lock) with one hand while braking hard.
I never use the sports mode, ridiculously brutal. I very seldom use the auto mode either, except when i let someone drive the car for the first time. In the driving section, the only slight criticism would be that the throttle blip when downshifting from 3rd to 2nd is a tad shy, but I am being picky.
Now here comes the downside: bumper to bumper trafic, constant stop and go's, manouvering to park in tight spots. Simply said, you don't have control on the clutch, and the car seldom seems to guess what you are about to do (a flying start or just move a few feet). Clumsy, clunky, my worst time in the car has been a long trafic jam on a uphill highway.
I have tried a M3 SMG2 and a Vanquish. They are clearly more refined, a bit smoother, downshift blips are perfect. The SMG2 in the sportiest setting can be blistering fast, but that's the kind of things you do with a dealer car, not with yours. The launch control system on the SMG2 is fun once, but I would never do that with my own car.
The 'double click' smart downshift of the Vanquish could prove more usefull in real life driving. Nonetheless, speaking with a SMG2 owner, trafic jams remain an awkward experience.
Now the question is: why not go for a gate and clutch ?
Never driven a manual 355, but I have driven several 550s. The gearbox is a special experience, you feel more ''connected", but driving real fast on windy roads is a humbling experience. Taking care of that stick is just the one thing you don't have time for in such a missile.
You can challenge yourself and deem the F1 box as a wimpy gadget, bottom line is that you're simply faster on a windy road with the wimpy gadget. I am not kidding myself, I am an everage driver, and I do better with a F1 box.
F1 cars have paddle shifters, rally cars have sequential shifters too, there is a reason.
Bottom line: think about what you'll drive your 355 for.
Every day car, daily commute ? Downtown snail trafic ? Take a manual.
Leisure drives, occasional drive ways, week-end or evening blasts, Grand Turismo in the full meaning of the word ? I don't think you will regret the F1 box.
Hope the advice helps :wink: