I think, from experience- it isn't, but I think I cropped more.
My own feeling was that the QHy 8 gave a 'warmer' vibrant sort of glow to the stars. They were post processed much the same. I have to say though- if someone comes up with a cooled DSLR mod that doesn't involve hours of tweaking (I have a shed corner dedicated to old TEC and heat sinks!), and doesn't weigh a ton- I am in.
Having said that, The QHY - I really like the colour representation so juries still out here.
