IE sound deadening, good stereos, even unpainted mirrors, door handles, and lesser amounts of paint (EVO only, but same principles apply).
LOL when I read "less paint and no painted mirrors" I think CHEAP! Honestly how much could a coat of paint on some door handles and mirrors weigh? A few grams? Thats their way of fooling you into paying more money for a product they put less effort and quality into.
Anyways... back to the point.
Coming from a CTS-V I would for starters not recommend the MS3. That would be a huge step down in car size for starters. Coming from a large four door car to a MS3 you will feel cramped and out of place.
Would I recommened a MS6, well yeah I certainly love it. The clutch problem is easily fixed. So no worries about that. There are some decent aftermarket stuff available, not a huge load of stuff. But you will find what you need if you choose to do so.
In all honesty, it sounds like you have some very nice cars.... as mentioned have you tried looking at a new S4? Or if you want something larger a supercharged (kompressor) Mercedes four door?
As much as I like my car I couldnt see rolling it next to a CTS-V and a Lotus.