One is a very old, rugged, and reliable Garmin 376C but there are no longer recent charts available and it's not compatible with NOAA Raster or Vector.
Yep, my Garmin 76cx has died and I wont replace it with a Garmin for the same reasons as you... their proprienty charts BS.
[Your Toughbook CF31 must be decades old? Whats it running Win 3.1? LOL. Time to upgrade that too, eh?]
All charts except NOAA are crazy expensive.
I love my OpenCpn on a laptop because I love the freedom, speed and accuracy of a mouse.
I have a trans Atlantic passage next year and am starting to think about the upgrading of redundancy. Im kinda thinking about a twin laptop, wireless (wifi) system linking everything. (Yes, I would buy a second wifi router for redundency).
Main reasons are that a new small fast laptop is just a few hundred dollars (OK about $300 to $400). Beware the very cheapest new laptops dont have USB connections nor number pads, so you cant use them with a wired mouse.
I find the iPad and smartphone apps too small or too paired down to use useful. but remember, I do lang range cruising and need different things than coastal.
Anyway, buying 2 laptops that are connected, but independent may be the way I go.