No matter how careful one is, the clips are prone to break when removing this shell. It's a design issue. Built to a price, you can't have everything. Fashion has it's drawbacks. Minor scratches during removal are the norm. A new replacement shell will tend to hide them.
Me? I prefer to use my MBP as Apple designed it to be used. Just as it came out of the box. Why hide it's good looks with a cheap piece of plastic.