That's the shot I used as reference.
I got TOPAZ lab but never tried denoise. Will download the free trial and give it a go. I find noiseware professional from imagenomic very good with a lot of control. I also have noise ninja, neat image and the noise reduction in startools on linear files. In PS noiseware gives me the best results. In the linear FIT/TIFF files startools does the better noise reduction.
PS: tried the trial version on 16bit stretched TIFF files. I think it does a real good job at that image scale. Sure there's a subtle moire in the background but nothing like the original noise. The rosette shot in particular has bad SNR (only 2h) and it amazingly still managed to clean that out. What do you reckon?