I have about 500 hours in the CJ2, and hopefully I can give you the answers you're looking for.
Air Conditioning:
The early serial numbers (up to around 100) have the Freon refrigerant, and all later models use R-0134 refrigerant. The system is okay, but you can forget any kind of cooling once the temperatures get 90+. However once you get airborne and in the mid-teens to lower 20's it works much better. Get to the higher FL's and the system will freeze you out of the cockpit! The blowers never seem to work real well in the cockpit (low or high gives you abotu the same low output), but the ones in the cabin work great.
Cockpit / Cabin Room:
I've also flown many hours in the 560 as well, and I'd have to say the elbow room is comparable. The 560 might have a slight edge, but it's not really that noticable. I fly with a guy who's about 5' 11" and 225, and we don't have any comfort issues in either.
In the back, the 560 I think has a much roomier and comfortable cabin. I've sat back in the CJ2 several times inflight, and I always thought that'd be an uncomfortable place to be after more then an hour or so. Big thing is leg room. If you have passengers who are sitting facing each other, both of you won't be able to stretch your legs out much more then a foot or so.
Fuel Burn / Range:
We hang out at FL430 and 450 most of the time, and you'll typically be looking at 320-340 pph/side. In the 30's you can generally count on about 450 pph/side, and the 20's about 550 pph/side. Tanks hold 3960 lbs. We fly out of the midwest (OK and KS) and we can go non-stop to the east and west coast without any problems. The west coast as long as the winds aren't too strong. If winds are strong, we typically stop over in Phoenix or Las Vegas for fuel. Last time we went to Long Beach from KS we landed with 1.5 hours fuel on board. On average it takes typically 2 to 2.5 hours to east coast, 3 hours to the west coast. The range on the CJ2 is published at about 1,450 miles. This is fairly accurate, as long as you have 2 or 3 people in the back. Take a full fuel and full passengers, and about 1,200 is what you can expect.
Noise Level:
Not too bad, although I have little other jet experience to compare it with. We typically take our headsets off and listen over the speaker once we get past about FL300. Below that and the noise is enough that it makes it difficult to hear the other pilot talking.
