Trying to decide which iPad to buy. I'm sure these questions have been asked an answered, but I tried searching yet couldn't narrow my search terms well enough to cull informed answers, so please help me with... ... two Noob questions: Does a 4G iPad perform better than a WiFi iPad with an unshared 4G MiFi? Related question: If you had a Verizon grandfathered unlimited 3G plan with a MiFi, would you keep it rather than "upgrade" to a data-limited 4G plan? That is,does an iPad perform significantly better in 4G than 3G? I realize the second question depends in part on several variables, but I am asking this as a general matter, aside from type of use, cost, and the amount of data used. Thank you.