I've used the SPOT Connect for over 2 years now. Hiking and overlanding, and at this point, I'm considering the inReach device. When hiking, its pretty much a gamble that the SPOT will get a message out. I pay for the tracking service, and find that on my backpack, facing mostly straight up, it still can't get a message out reliably in any kind of dense vegetation. I've gone on entire trips that I wanted to track my progress on only to find that as soon as I entered the trails, no track existed, until I was almost at the exit of it. So with an inReach, at least I would know that my messages are not being acknowledged, and can move to better ground.
Now, the custom messaging on Spot Connect is nice, and helps, because you can message someone and say, "Hey, I'm stuck here, need a driveshaft" and you can use your phone to make them up on the fly. But, again, with inReach, you can receive your contact's response that says "be there in 2 days." With SPOT, you twirl your thumbs and hope for the best, so having to hit the SOS button for things that were not an emergency that became an emergency seems more likely.
With SPOT service, + tracking, + some insurance thing, I think I'm hitting like $180 a year. I am no over the tracking feature, sure its cool, but most people don't care. Those who want to know where you are, generally want to know if you made it to X location on X date or time, not so much the path you took in a crude fashion. If they want your path, they probably want a detailed GPX.
So, inReach seemed more expensive at first, and with tracking and all that, seemed cost prohibitive. But, after all this time, now I realize that I don't really care much for tracking, and that 2 way messaging and message confirmation indicators are truly better for when a real emergency or situation where you need help arises.