I don't have setters but used to run a grooming parlour. Setters and cockers seem to be the breeds worst affected by change of coat after neutering.

They tend to get a apricot coloured fluff/frizz and lose the glossy flow. I used to have to clip a few of the older ones whose coats had become a real challenge with matting. the natural coat is much easier to handle.

If i had a setter i wouldnt neuter unless i absolutely had to and then after 2 years.