I bought the older InReach SE (on ebay for about $200) It doesn't have the map display features of the Explorer; it requires a bluetooth connection to an EarthMate app on my cell phone.
But anyway, I have both a Spot an SPOT II that I'd like to sell (for almost nothing if anyone wants either one) The SPOTs require an annual subscription, which in the long run costs more than the unit.
The InReach has various levels of subscription, more flexible, but no way less than the SPOT subscription. My cheapo level with InReach is $15 per month if I don't use it. If I use it on a trip, they ding me a few bucks extra, since each message costs $.50 or something like that. Tracks cost a dime each.
But anyway, I bought the InReach because of its 2-way texting capabilities. That gives me (and my family) peace-of-mind that I won't just vanish on a trip, and can let people know if I'm in trouble.
From mountain tops, the satellites are easily accessible, so messages transmit right away. Down in canyons, you might wait 20 to 30 minutes before the unit can "see" a satellite to send/receive a message. SPOT signals are similarly temperamental.