The ECS plate will provide a good amount of protection. It bolts to the frame in the rear and is attached to the bumper and wheel well liner with screws along the sides and in the front. There are also tabs in the front that interlock with the bumper.
It's not a flimsy piece of crap like some people seem to think. It's made of 3/16" aluminum.
I have one and have scraped it and had plenty of rocks bounce up into it. It can easily take hits.
You don't get it...
LOOK at the picture very closely...there are two nice bends/ creases in the pan before it joins the subframe...these are the weak points as if something hits the pan it will hit the main section in front of these bends/creases...
One of those bends is "upwards" so will flex upwards easier than in the other direction... this is into your oil pan....the ONLY thing resisting this is the strength of the wheel arch liners & the front bumper under trim....
Basically if I put a wooden plank across mine at the front & jack the car up it will be fine....the ESC one will flex at the rear bends & split the wheel arch liners etc...& then hit your oil pan
I did structural engineering at uni...& that ESC pan does not fully meet the design requirements for a "skid tray" IMHO!....