I too have had the urge to downshift to increase the rpms when I find myself in the same situation. My 606 engine (non-turbo) seems to bog at under 2000 rpm and I don't like to floorboard the accelerator to achieve just a little pickup.

I have tried the downshift a couple of times (very successfully I might add and it felt like I was contributing to the driving process!!) but wondered if MB would frown on this (I can't see why) but in reading rwthomas1's question I echo it.