I have raised only two batches of chicks: one artificially indoors, last spring, and another this spring, hatched and raised outdoors by broodies. It seems to me that the naturally brooded chicks grew and matured faster than the artificially raised ones. We handle each chick every day, so they seem just as tame as the artificially brooded ones (and it helped that the hens that were raising them were tame, too....that's something else the chicks seened to learn from their parent).
The ones raised outdoors have been getting plenty of fresh air, sunlight, exercise and "treats" that aren't on the list of approved treats...lots of nasty, juicy, bugs. I was so nervous about what I offered the artificially brooded chicks!