I have the regular InReach SE, the Earthmate app, the OnX hunt app, and a Garmin GPS unit with state specific OnX chips and tried using all three last year. The InReach SE works well with the Earthmate app and I used my smart phone to send messages back and forth to my wife everyday, several times a day, for 10 days to my wife. The GPS function of the paid Earthmate app is ok, but it does lack landowner contact info and unit boundaries. I haven't tried any of the updated versions, but I didn't care for the layout either. The free version is only good for messaging and excels in that regard. The Garmin unit with OnX chips were the easiest to use and I liked that I could change out the batteries and had boundaries marked for every unit in the state. What I didn't like is that I couldn't get satellite imagery for new units when I decided to try someplace new. The OnX hunt app for the smart phone is the best thing going. If you put your phone in airplane mode, the GPS functionality still works even without cellphone signals and the ease of use is awesome. The downside is that a smart phone still burns battery life like nothing else, so you need to have a solar charger with battery pack or large battery pack to charge it every night. Another downside is that you need to download all the maps and images for your hunting unit before you head out if you will be out of cell service. I hunted the north and south slopes of the Uintah/Yellowstone units in eastern UT and the Ogden unit last year. When I moved from the Uintah's to Ogden, I just downloaded what I needed in Ogden before heading out again.
After testing each one, I found what works best for me is the InReach SE paired with my smart phone with the free Earthmate app for messaging and the OnX app for GPS navigating and tracking on my smartphone. The OnX system, literally all of it, is worth it in my opinion. I am not elk hunting this year, but I hope to try New Mexico or Colorado next year. For that, I will happily pay the $99 for the OnX yearly subscription. That is money well spent for a flatlander hunting out west.