Sorry, I don't have any information on UK tests, but if you are looking for sports cars, you should easily be able to compare whats out there just by visiting the competition (Viper, NSX, M3, Cobra, RX8, 350Z, EVO, WRX STI) Really the Z06 doesn't have any competition in its price/performace range at this time. The Cobra is the closest in performance and price....... if you want a Mustang. The Viper is a great car, if you have the extra $35K+ I would say go for it. Actually I kinda like the 2002 and older Vipers over the new SRT. If you want a nice interior, go with the 350Z, RX8 or M3, but expect performance levels below the LS1 'vettes. Personally, I looked at the Cobra, Viper, M3, 350Z, NSX and WRX. I wouldn't trade my Z for any of them, not even the Viper. The interior of the Z does not bother me one bit. Its very functional, easy to clean and easy to work with. I used to have a 300ZX with a great interior, but it was a bitch to clean the velour and smooth plastic stuff.
I have no idea what horrendous maintenance and insurance costs you would be referring to. The only expensive maintenance item is the tires, but no more than any other performance tire in its size and class. The LS6 uses synthetic oil, so oil changes are not $19.95. A lot of us change our own oil, so you can save money there. Insurance costs are the same or lower for a comparable 2 seat Hi-Performance Sports Car. My wife has a 2003 Accord ($20K car) and her maintenance and insurance costs are the same or higher (except for Comp coverage) than my 'vette. And Honda just had a recall on the new Hondas

, so I rib her about that.
You are very close to the January intro of the C6, so you might want to hold tight for a few months. You will probably either want the C6 or you could find a Z06 for a better price at that time, depending on how the C6 turns out. Rumor is the C6 will have a better interior and "similar" street performance as the Z06. Expect the C6 to go for MSRP or higher for the 1st year. Currently you can get your choice of Z06 from our fine Forum Vendors for better than $6K off MSRP.