@ Quinton, I have no experience with the two models mentioned. There are lots of reviews on the web of most electronics. But I think the most useful thing you could do would be to write down the 10 things you want the GPS to do and go to a bricks and mortar store and try out the models and see if they can do what you need. After that, battery life and the ability to recharge from a USB battery would be at the top of my list. Second, I have heard rumors that the latest model of the Garmin InReach will include full Garmin GPS functionality.
It might be time to upgrade your InReach for about the same cost as a new GPS and then just carry one device. I have the older model Garmin InReach and since I also use paper maps especially in the UK and Switzerland, its main limitation in my mind is its VERY limited support for map grids and map datums and its bias towards displaying latitude and longitude.