This thing looks promising, I ran across it today:
https://www.kickstarter.com/projects...lt-for-adventu

It pairs to your phone via bluetooth and you use your phone to send/receive text messages using their app.
Like the inreach except no screen / GPS navigating functionality
Dedicated SOS button, doesn't require phone pairing for SOS.
85g (3 oz.)
$15US/month for 20 messages, month to month (so you can put it on hold in the winter)
$450US MSRP, but $320 on kickstarter
Built-in battery, USB chargable, 1000 messages per charge
Iridium satellite network (Same as Inreach)

I currently have a Spot and have had no problems with it (except the fee increases), but the light weight and 2-way communication capability of this unit makes it appealing.