If you have done basic yard work, worked with release birds, shot over, assuming all that, I would take a pup on a small scale hunt without reservation. No 15 man, 30 dogs, people screaming, blowing whistles, growly other dogs affair, with random gunshots of undetermined origin or reason, from the dogs perspective. I would take a pup afield, as soon as they can negotiate the cover, consider it happy time, let things unfold as they will. As far as O/U's I am a little unsure of your dilema. O/u's not shooting to the same regulated point of impact, is a thing of the past, due to laser bore sighting and precision. In the old days had to be hand reamed, shot, reamed again, regulated as they call it. You can spend anywhere from around 1000.00 to 150,000. on an over under, difference is reputation, fit and finish, type of action, sidelocks are more expensive, and of course engraving. That said one heck of a lot of birds have been brought to the table by Remington 870's. So it comes down to your preference and what you shoot well, unfortunately sometimes not one in the same.