Like everyone else said, it depends what you want. I'm 43 years old, and while I love the MS3 and it's faster from a roll, I just can't see myself in it. The MS6 is refined, avoids the boy-racer look, and has enough pickup to be fun. Would I take on an Evo or an STi? No. But at this altitude, I keep up with Mustang GTs and G8 GTs, and leave 350Zs watching my taillights (stock against stock, of course).
However -- there are days I wish I had the convenience of a hatchback. LIke when I want to take my dog with me somewhere, or have to get something big. Then I remember the CX-9 in my garage and the Grand Cherokee in our driveway and I'm over it.
The MS6 is hella good in the snow. I drove all last winter on summer tires and did just fine. I can't WAIT to try it out this winter with Eagle GTs on it.
However, the MS6 is quirky and has some weakpoints that can cost some $$. The smoking turbo problem is convenience only, but the weak rear diff mount and glass-like rear axle (ok...overstated...) can cost you some serious bank if you're modding and break them.
You know what I like MOST about my MS6, though (besides being sexy as hell)? It's truly a limited edition car. Not made any more. ANd I believe something like 7500 - 9000 made it to the US, with 15K made worldwide. So it is kind of a collector's car. While the MS3 imported only 15K to the use in 2007 and 2008, it looks like it will continued to be produced (that hood-scoop model looks HOT), and it has definitely sold better than the MS6, thanks to being well-priced in a crappy economy.
Anyway...that's my 2-cents-worth.