The lifter is not about avoiding scratches . Even with the lifter you scratch the lip ( at least I do, and not only once, many times )  

The lifter is about not being stuck in unknown situations ( as mentioned above ) or having to go side ways on numerous speed bumps . 

If you use your GT2 RS only for the track , then I would not get the lift . If your GT2 is going to be driven everywhere , then there is no hesitation , get the lift to have peace of mind .  The cost .... humm, 0.8% of the value of your car ....

I'm not convinced that even on the bumps the lift is helping... 
But as with Porsche "less is more" is a principle :) So i will take the lift  and make a 7kg diet

Just FYI : 

Lars didnt had any lift on the yellow records breaking car.

Gt2.PNGlift off.PNGlifton.PNG