I purchased this some months ago, and this was my first experience with a tbr product.
The skid will indeed protect from direct impacts, but it wont give full protection from little rocks and debris as these can easily fit between the chassis and the skid. The reason is that the product will not be a perfect fit once screwed. I believe there are 2 reasons for this:
1. while there are 4 screws (2x4) at the extremities, there is only one at the center, and nowhere else.
2. the holes have the concave part to fit the screw, but dont have the convex side to actually fit the chassis. This also make it more likely to break screws on impact.
These 2 reasons cause tensions to the skid, and it'll cause 2 "bumps" (from the center to the extremities). Causing a lot of space between the chassis and the skid, where debris can enter and damage the chassis over time. Note that these 2 bumps, will even get bigger while doing jumps because of the flex of the chassis and the fact there is only one screw at the center.
Also, because it doesn't perfectly fit, water will go there (difficult to remove) and cause corrosion to your chassis over time (aluminium wont rust, but it can corrode.)