hi col,
i am pretty sure Richard M did a lot of testing on cooled vs uncooled dslrs.
a melbourne winter might help but i don't think it was too promising for uncooled dslrs past 2 or 3 minutes.
on a side note - if you have ever wondered what a 30 minute exposure of the helix looks like with a Ha filter on an uncooled dslr @25degs i have the answer here
https://www.flickr.com/photos/803366...blic/lightbox/ ... very difficult to see the noise!! haha