Last winter my worthless all-season tire can't stop the car so I hit a pile of snow. I cracked mine more than half an year ago without any aftermarket lip on sale. Fortunately it's not too bad so I installed a HTauto lip (not cheap though) then the cracked part is almost invisible.
The lip is aggressive so whenever I go down a ramp, I hear the lip hitting the ground, but the lip is strong and flexible enough to avoid any physical damage other than some scratches which is still invisible if you're 1 foot away. I think the flexibility of the lip can somehow cover your bumper but it doesn't mean it won't happen. In addition, this expensive lip extending out of the body will hit the curb first before your more expensive bumper does, so I think it's a better investment than OEM. The OEM replicas might be a cheaper way to go but I don't know how they work.
It still depends on how carefully you drive to avoid collision. I agree the drivers take the full responsibility of cracking bumper since this is a lowered car and you like it so you buy it. WRX owners will not appreciate that their cars are as high as Outback Sport. Well, maybe that's the way Subaru should do to make people lower their car by their own and clearly disclaim any responsibility.