I'm choosing between the base iPad 3 (wifi + cellular) and 4 (same), 16GB, because my parents could really benefit from the retina screen. The refurb prices differ by $70 ($409 v. $479), so I'm wondering whether to pay the extra $70 for the 4. My parents' needs are minimal: very basic needs, so 16GB will be fine for them. I generally know the differences between the two, but I'm leaning towards the 3 because $70 saved and no loss of features that they would actually use. Thoughts?