Most folks I know with a notched tailgate have one because they already crunched the original. And the notched replacement is usually cheaper and easier than an OEM replacement and paint.
I see no advantage to having a notched one.
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD 4dr short bed Duramax w/allison
Reese Fifth Airborne air ride king pin coupler with Sidewinder