Depends really.. what do you use the car for? Is it a drag car? Is it a drift car? or even a track car? In most cases, reducing the weight of the car can give you noticable performance gains, handling is one of the main gains people will see when switching to (C)FRP bonnets.
I really don't see the need for it if you're the kind of person who uses the car to go to the pasar every weekend. Plus, I have heard about someone who got their CF bonnet stolen from the car, and it was parked in their own yard (does make one wonder if the bloke has an alarm system installed.) Too many itchy hands.
Stay away from having 3-4 gauges on the dashboard. Buy small digital ones instead, so you can hid it when you decide to park in a dark alley :P