We have a 300m and a Crossfire in the garage. I have a long commute every day, so there are days the 300m is great. But it really depends on your proirites.

Crossfire
Better NVH
More fun to drive!
Better fuel mileage
Engine sounds great

300M
More comfortable on long drives
More room
Better visiblitiy

If you can do with only 2 seats, my advice is to get the crossfire!

Andy