As A-train said, you don't know how thick the paint is, so it is difficult to know how much paint you can afford to sand off. Looking at the bumper in the pics, I would feel comfortable sanding 40% of it, and might do 50% If i really wanted it to be nice. 60% removal or more would make me very nervous. If you just removed 40-50%, it would make a huge difference in the appearance. It wouldn't make the peel go away completely, but that should be enough that it won't be eye catching anymore, and when you look sat the car, all you will really notice is the color and the shine. If you took half of it off, you would really have to look close at it in order to see it. At 50% reduction, that is still on par with some Ferraris, like the white 458that koniyoto did recently.
http://www.autogeekonline.net/forum/show-n-shine/58114-ferrari-458-italia-new-car-detail.html
Look at pics 13 and 16 in the thread. That is white, so it is less conspicuous.
If you do decide to sand this panel, stay away from all of the edges. The paint is liquid when it goes on, and as such, tends to run off a bit from those areas, making it thinner than flat areas.
Aim for improvement, not perfection. If you go for perfection, particularly around edges, the chances of you sanding through the clear are near 100%. There is another thing that you might not have considered, and that is that despite the intentions of the designers of the car, when parts come out of the mold, they might not be perfectly straight or perfect. There can be slight waviness in them, which are effectively high spots in the material that you can't see. I speak from experience.
If you try to sand the whole thing perfect, the sandpaper can go right through the clear, when all you are doing is trying to make it smooth, and assuming the whole panel is shaped perfect.
Again, don't sand the edges at all, and only try to reduce the super high spots of the peel.
You have to weigh against the possibility of going through the clear, as well as considering that you may well be polishing the car a few more times as you own it, and sometimes having a little orange peel is an acceptable trade off in order to have a thicker coat of paint for a more long lasting paint job.