Quite good. Install was a breeze. Once it's in and all hooked up it just does it's own thing. It's successfully isolated a drained aux battery from my starter just like any dual battery setup (and vice versa when I had a parasitic drain on my starter it isolated it from my aux). Granted I have a lithium so that charges super fast, but the voltage boost from the Redarc works well from what I see. I wired in the solar but only tested it so far. No field use yet, the lithium has power for days. But if I was camped for more than two days I'd throw the solar panel out and be golden as far as power is concerned indefinitely (or until the Lithium craps out in a few years).
The only solution I still need to work out is a monitor for solar. Not a huge deal but I'd like to know the juice flowing into the unit via solar. I can easily add a voltage and amp monitor, I just haven't yet. Manual jumping from one battery to another is another thing it can't do out of the box. Not a big deal for me as I always have a lithium jump pack in the rig but some people might want to link both manually for whatever reason. Extra winching power I guess? But it links both batteries while running anyways and you're probably not winching without the motor running. You can still manually link but you'd need the Redarc SBI. Which I actually have from my previous setup, but I removed it when I put the BCDC in.
The upcoming 110VAC Manager30 sounds cool but you'll still need an inverter and the unit is very expensive. My GoPower and Redarc BCDC does everything the Manager30 does minus the monitoring. Also the Manager30 is about 6x the size of the BCDC but about the same total size as the GoPower, sorta. And the GoPower is an inverter, switch, and charger all in one and it can work with the BCDC with a few setting changes.
All that said, the best purchase was the lithium battery. If you can swing the initial purchase it's 1/3 the weight, twice the capacity, and has a longer life than a conventional AGM. The thing is magical. And no issues with heat in the engine bay during Baja or Moab.