OP, thanks for the nice review!
I think both the Cirrus and C310 are pretty darn good airplanes. I always enjoy a good single v. twin debate, knock yourselves out guys!
As someone involved in the care and feeding of 1971 C177RG and two 1978 PA28s, I'll say this.
I think there are real advantages that come with flying an airplane that doesn't remember two dollar avgas.
As these airplanes get old a lot of little stuff wears out. Doors don't fit as well as they used to, and door handles and locks break. Wing ribs can have issues. Push to talk switches wear out. Plastic rots. Fuel tanks have issues as they age. On and on.
You can take an old airplane, overhaul an engine, put in a fancy gps, add new paint and interior. You have a really nice looking old airplane. It's still an old airplane with a nice gps and paint job. It's going to have lots of little things and occasional big things breaking, or at least aggravating you.
Life is short, I can sure see the appeal of a brand new airplane for those with the mission and the money.
I can also the appeal of a fully rebuilt airplane, such as the AOPA and Skyport Cessnas or the Nextent jets. Those might be the best buys of all in their respective classes.
Edited to add: The only civilian twin I have any time in is the Dutchess. It flies pretty well on one 180hp engine. I was thinking about this 'Big Blue Banana' thing the OP mentioned in his review.
Even if you assume that your Dutchess can't maintain level flight on one engine on the day you have an engine failure in cruise, I promise you that your 'Big Blue Banana' will be a LOT bigger than that of any single engine airplane, from a CT to a PC-12.