I have docked and done dews on quite a few litters in my time( I did it for fellow breeders as well, not just my own ), and found that while some pups *hollered* a great many did so because you had to hold them so still, they cried long before I put the hemostats on, so while I am sure it not pleasant I am not sure it is all that bad. They usually happily go back to nursing as soon as put back with Mom. I don't like it when people wait too long, I made that mistake once and those pups did seem to feel it!
I have seen that many times, breeders who went to ves for docking had more issues with infection, stress etc. So I prefer to dock/dew them at their home so they and Mom are not stressed by travel!
Having said that, I do have 2 JRTs with full tails, my first Mindy, and Max whose litter I was supposed to help the breeder dock, but he was a singleton and not well, so he did not get docked. I love them tail and all, but I always worried when Mindy was backing from the earth about her tail bending back and she was very hard to *tail* in the earth as her tail was long and awkward, tailing a docked JRT ( So long as they do it right and not too short, a JRTs tail is supposed to be a *Handle* of sorts ) is much easier.
So while I have no problem with full tailed dogs, I do prefer docked tails for docked breeds most of the time.