The only issue I have found having the full lower 48 loaded is that when you haven't flown in a week or two and decide to perform a quick update you might be stuck at the computer for up to an hour pulling all that data onto your usb or sd card.
I have started performing all my updates on the pc using two SD cards. One is in the airplane with the ifly and the other is at home. When I head out to fly I update the one at home and insert it into the ifly before I start up. The one out of the ifly goes home with me and gets updated before my next flight.
Works like a charm.