My son will be 7 years old in 1 month and I wanted to give him an iPad. He will only be using for reading books and using educational apps and some kids games as well. Should I get an iPad Mini (non retina and smaller display but lighter) or should I get him an iPad 4 (retina and bigger display but heavier)? I would be getting the Wi-Fi 16gb so the difference in price from $329 to $499 would not be an issue in my decision. Tks for any help.