Over the last couple of years, I have been downloading topo maps from the US Forest service for the BWCA from the app as back up to my paper maps.....newer additions cost $.99, but have much better detail than the usgs maps for the same area, even showing portages and campsites.....with that said, that may not be the case across the board.....I would suggest looking at all maps available for that area you are traveling through and see who offers the most current version.
Mike