@singleview, I've been where you're going. I have owned two MB E-Class cars over the years. My current one is a 2010 E550. I was considering the 2017 E300. But, I mainly declined because it lacks the power that is conducive for the way I like to drive. I would wait for their release of the E550 next year, but then, it's an ICE, which is the most favorable aspect of the Tesla MS.
I still have the E550. It's a fantastic car. MB's 2017 E Class is also fantastic. But, the Tesla MS is a better choice as long as your priority is not luxury. The 2010 E Class had very little luxury unless you had the Designo option. Materials in the 2010 E is virtually all plastic. This I don't mind because my priority is performance. MB has brought back higher class materials in the 2017 E Class -- a bit more plush than in previous years.
The MS P90DL costs a LOT of money. But, performance costs. And, you at least get the performance of quickness with the P90D. Handling is a matter of getting used to because it is such a heavy car. Breaking is not there for a car this quick. Air suspension is adequate -- would be nice if it were adjustable. All in all, it is very good. Can't say it's worth the price. But, it is certainly unique - quick, full-sized, electric sedan -- no other car can say that.
But, Tesla truly missed on the most basic, simple accessories and options. The MS is not luxurious -- but, why not? Why not have luxury options? Then there are the WTF Were They Thinking items: no coat hangers; no rear cupholders; no rear center armrest; no lighted vanity mirrors; no door pockets; no ventilated seats option; no spare tire option.
Sure, can live without these basic things, but really?