In the 130J community we have moving maps for JOGs and such.  Mostly used for tac.  For other flying, it's a great SA builder because we can overlay our position and our flight plan. I'd imagine the iPad moving map would be similar.  Mostly just an SA builder, and a way to keep organized.   
  
As for your frequency dilemma, I'd imaging that we would be backing up our iPad for a while.  Similar to how we still back up GPS with ground based nav-aids.  (Is that still done in most communities?  Our GPS isn't certified so we have to back it up to be legal).