Please don't change the gears in the 300D either. Tall gears are a real joy on the highway. At 65 MPH in my 400E, if I nail it I get a 2 gear kickdown clear down into 2nd and the car is unbeatable in that mode. My bud's 500E with 2.82s won't do that on the freeway at all, even if you try to do it manually. Most of my skirmishes are from a roll anyway. That's just how it seems to work out in the real world.
When I'm in that 500E, I'm always looking down at the shifter to make sure it's in drive cause it always seems like it's stuck in third.
Shorter gears also make a car more prone to wheelspin. You don't need short gears to go fast and have good acceleration. At a dead stop, as long as I'm pointed perfectly straight, I can hit the gas as hard as I want and the car won't spin. No special feathering techniques, no ASR required. Just punch it while doing the Sammy Haggar grunt and go. My 14.4s correct to 14.0s BTW.
You'll love my 300Es though cause they are rust free California cars and were made while MB was still putting 3.07s gears in them (90 and later ones have taller gears). 3.07s combined with that spare 5 spd overdrive that you already have would make a low gear lover like you pretty happy. These also have a higher redline than even your 400E does!
We can run the 300D against the 300Es when we get together to do the trade. My money's on the 300Es!
Regards, Eric