I can't stand the whole efficient dynamics campaign. It's an insult to anyone that actually knows cars. "Oh hey look. We limited your throttle input to half and you gained .5 miles of range over the last hour!" That whole thing can go away. Where you lose me is with the turbo motors. Yes, the naturally aspirated engines do have a certain flare to them but the turbo motors are obnoxious in their efficiency and power. As far as the unevenness goes, the turbo cars have really flat power delivery so I'm not sure where you're getting that feeling from.
I sold my M5, bought a 6 speed manual 550i to tie me over for a year and then got a 2010 535 after hearing about how the twin turbo 6 responded to modifications. With just an E85 mixture, a tune and an intake that car put down 470hp at the crank with equally obnoxious amounts of torque. It was insanely fun, faster than the M5 in pretty much every street driving metric, still mustered 30 miles per gallon, was really reliable and oh boy... I miss that car. I regret selling that car.
I loved it so much I wrote an article about it that pissed off a handful of M5 owners. :-D
10 Reasons The E60 535i Is Better Than The M5