Maybe something has been lost in resampling here are 100% size crops:
http://www.pbase.com/terrylovejoy/im...76161/original
Also I attempted to adjust the levels to match the difference in electronic 'gain' between the 2 cameras.
http://www.pbase.com/terrylovejoy/im...76915/original
Processing steps are outlined in detail in both images. All images were acquired in raw mode by Wayne Cosshall from near Geelong in Victoria and were made almost at the same time from the same location. His recorded settings were all confirmed in the exif data. Why is this not legit test? The OP wants to know comparative performance for astrophotography.
Its possible to do excellent astrophotography with either camera, but you will just have to work slightly harder with the Nikon.
Terry