I picked up the 7D in the end. Its a very solid camera. Haven't had a chance to test the ISO noise but it does seem pretty sensitive. A 10 second shot in light polluted Cherrybrook picked up a few stars in my 450D. In the 7D it was washed out by the background light. It seems much more sensitive even at the same ISO setting. Hoping to take it to Wiruna this month to try out. Its tack sharp
http://farm9.staticflickr.com/8309/8...055cab17_k.jpg