I also use the premium version of Gaia on an Iphone 7. I make up my maps/routes/waypoints on a laptop, and download to phone. Sometimes I print maps from my laptop, then they exactly match what's on my phone. I can get a week or more from the phone battery, taking a dozen or so pics a day, using Gaia to check my location a few times, and taking it out of airplane mode once a day to send a few texts. I do carry a power bank, and recently added a Zoleo satellite messenger because I know my next trip will be where there is a vast lack of cell service. I had a dedicated gps device, it was hard to use, clunky, and heavy. Unless you're not planning on taking your phone, or it's battery life really sucks, there's no reason that I can see to have a dedicated gps for hiking/backpacking.

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