Thanks for the subjective info, but it's completely useless.
How about some objective measurements?
Edmunds test of the Model S:
2015 Tesla Model S P85D Road Test Specs | Edmunds
Braking comments Fantastically sticky summer performance tires are on display here, but give credit to the brake system as well. Even though the pedal exhibited the kind of "dead" feel we usually associate with electric vehicles, and a longish amount of pedal travel, the distances stayed consistently short.
The first run was 104 feet, the fifth run was the shortest at 102 feet and the sixth and final stop was 104 feet with zero pedal fade and minimal brake odor. Each stop was drama-free, without any side-to-side squirming.
Edmunds test of your E500 with SBC:
2003 Mercedes-Benz E500 Road Test Specs | Edmunds
Braking comments The electronic brakes being fitted to new Mercedes-Benz products are undeniably effective in terms of stopping distances.
Our test car stopped in 120 feet on its first braking attempt and 124 feet on its third and final run, so fade was nearly non-existent. However, braking feel remains an issue with this system. When pressed into maximum service the pedal gave minimal resistance for most of its travel, and then got "squishy" as it neared the floorboard and stopped moving. The upside is that there was absolutely no ABS vibration in the pedal, and the only noise to be heard was a slight whine that continued for a second or two after the car came to a stop (the whine was completely inaudible as the car slowed). Bottom line: these brakes are great in terms of outright function, but they need work in the "feel" department, even if improving them involves fabricating the sensations normally associated with hydraulic brakes.
Consumer reports test of the Model S:
Tesla Model S P85D Test Results - Consumer Reports
Braking
No track testing is done before the vehicle hits 2,000 miles, and we perform a brake seating procedure the day before we take measurements. The test procedure is done on special areas of our test track that are monitored for consistent friction and involves over a dozen stops, with cool-down laps in between to ensure accurate results. We begin measurement as soon as the driver hits the pedal, and the distances are adjusted for temperature.
The P85D stopping distances were very short, like a high-performance sports car at 118 feet in the dry and 129 feet in the wet with the optional 21-inch wheel and tire package.
Braking
Excellent
60 mph Dry
118 ft.
60 mph Wet
129 ft.
Consumer reports test of Mercedes latest and greatest 2017 E-Class:
2017 Mercedes-Benz E-Class | Reviews and Ratings from Consumer Reports
Braking
Excellent
60 mph Dry
128 ft.
60 mph Wet
143 ft.
So, the Model S is better under all tested conditions than all tested Mercedes E-Class.
Also, worth noting that Mercedes ditched the SBC system and went back to traditional hydraulic brakes after recalling over a million cars with SBC for pump failures.
Sensotronic Brake Control - Wikipedia
Good luck with that though.
You're far better off in your Model S.