I didn't have Clear bra installed on my car, but IMO whether or not you need it depends on what you want with the car and how/where you use it. If you DD the car and/or drive on some roads where there are a lot of little rocks and pebbles flying around, it is more likely to get rock chips. The clear bra will definitely help, but it will not protect against everything. Some of the bigger and harder hitting rocks will still go through it, requiring you to replace it. If you don't DD the car and want it to remain in perfect condition, then go for it.
My car is a DD and gets hit by rocks a lot on my commute, so I didn't do the clear bra. I thought it would be a lot cheaper to just eventually repaint the bumper or even get a new one than to clear bra everything.
I hope this info helped and good luck
