I believe people's opinion depends on location. I think somebody living in Florida would feel differently after living above the snowbelt for a year. From November to April, there is a constant layer of small rocks and pebbles on the roads and your car is subjected to a sandblast of that stuff whenever you take it on the highway. The cars in front of you kick it up because it gets caught in their tire treads. Forget about trucks, my car gets pelted with rocks from trucks 1/4 of mile in front of me when they don't have any mud flaps.
I only put the clear bra on the front bumper of my Audi. No where else. It's never turned color and nobody can detect it is on there.
IMO, the F30 design is really made for a clear bra, especially with it's hood line. If somebody puts a clear bra on the bumper and only the front plastic section of the hood (where the BMW logo is located) it would be very hard to detect any edges of the clear bra. Just don't put the clear bra on the main metal portion of the hood. That would be too noticeable and it's not really necessary because its approach angle is mostly horizontal anyway.