Hi frankyknuckles, I've just been through the same process myself and was looking at the same list of potential cars before choosing the Z, was a tough process (mainly as I'm 6'4" and 17 odd stone and struggle in most cars of this style).
Pleased to say I took delivery of my shiny new MY06 Roadster 2 weeks ago and haven't got the smile off my face yet.
A quick google search will return a ton of short reviews, the main sources I used when comparing models were Parkers http://www.parkers.co.uk/choosing/carreviews/review.aspx?model_id=1331 (sorry roadster review) and 4Car http://www.channel4.com/4car/road-tests/road-test.jsp?id=288 I know these are both fairly middle of the road consumer sites, they do however give a lot of information that can be directly compared with other makes/models and focus more on the day to day aspects of the car
Dull bit out of the way
Buy one and buy one now, fantastic car, great grunt, great looks and oooooh that noise!!
Cheers
Barry