Kevin_A I'd say it depends on the price. Yes at gain 252 the camera is pretty noisy, but I have had good results at gain 100 with longer exposures. The FWC at gain 100 is about 12K. Read noise twice that of the 533 at 100 gain, but not so important with longer exposures. The DR is 11.5 at gain 100 compared to 13.5 for the 533.
So yes the 533 is a much better deep sky camera, but if a 585MM Pro can be around 60% of the price of a 533MM Pro it might be a good deal.
For ZWO: it might be nice if the HCG could be a bit lower than the 252 gain setting.
