I have the Garmin inReach Mini and based on your needs, I think it may be better suited for you than the SE. All of the inReach products use the same Iridium network and you definitely have to be outside in order to sync with the satellites.
With the Mini, some cover (cloud/trees) is tolerated but ideally you want a clear shot of the sky. What I don't know is if the SE antennae has a stronger gain (better reception).
Couple other notes - battery life is significantly better on the SE. It also comes up with maps on a color screen. Both can be paired with a smartphone via Bluetooth. The difference is with the SE, you can do without it as far as sending messages. On the Mini, it's certainly possible to type out a message but it's a lesson in frustration...especially in an emergency or urgent situation.
With the SE, you get topo maps and full GPS Navigation functions.
For me, I'm ok with the battery life on the Mini. I always carry a USB charger anyway. I also don't need maps and navigation (I use OnX and Google Maps on my phone).
So basically, if you need an all-in-one GPS and communicator and you want excellent battery life, then the SE is for you. If you just want to send messages and/or share GPS locations to your friends and family, then the Mini might be better.
Both of them have the "I've fallen and I can't get up!" button. If you get in trouble and need an evac or medical assistance, you hit the button and the device alerts the search and rescue monitoring center.
One last thing - the subscription plans. There's a bunch. I went with the Freedom plan as it allows me to suspend the account in the offseason (saves a bunch of money). You can activate/deactivate your account anytime via the Garmin portal. There's also the option for pay for additional insurance
Hope this helps. Sorry for the lengthy post
