I, too, have an EX-L, and will be adding the backup sensors. At certain sun angles, you just can't see ANYTHING clearly in the backup camera. Plus, I back out of spaces by first looking at the camera, then turning my head to look rearwards throughout the movement rearwards. The backup sensors will help augment my situational awareness as I'm backing out and my head and eyes are looking out through the rear glass.
One concern is when I'm backing up in a crowded parking lot, first put the van in reverse, check the camera and see that it's all clear, turn my head and eyes to the rear and look out the back glass, start backing up. Somewhere between looking at the backup camera and then backing up, a kid could suddenly appear right behind my van. I didn't see him in the camera. I didn't see him when checking left and right as there are cars parked next to me. And definitely didn't see him as he was shorter than the back glass of the rear hatch. It only takes a split second. Even for those that keep their heads on a swivel and alternate between looking at the camera and looking out the back glass.
For me, this alone is reason enough to warrant the cost of the backup sensors. It's an additional level of safety that I'm willing to pay for. But, your mileage may vary...