I don't have any R25-specific info for you but we have Victron and Balmar battery monitors on our R27OB, both monitoring the house bank. You can "stack" the shunts by wiring them in series.
Our Balmar gauge is mounted at the helm. The Victron gauge has been "temporarily" mounted behind the helm for three years while I decide if it's worth cutting another hole.
Reliability - I installed both monitors. We had an initial install problem with one of the Balmar connectors, but after that was identified and fixed, it's been rock-solid for four years. The Victron has not had any issue.
Use - The Balmar gauge is much easier to use and read. As it's mounted at the helm, I use it 90% of the time to monitor the battery because of the convenience. The Balmar system is able to be expanded by adding additional shunts and gauges, should you need that capability. The Victron gauge provides more detailed info, e.g., history, trends, etc. and can be montored remotely via Victron VRM with the right gear, but its a bit more clunky to use. I access that shunt via my phone when I need that info, rather than the gauge. It also integrates with all of the other Victron gear on our boat in a way that Balmar can't. If I were doing it again, I'd just use the Victrom shunt rather than the BMV-712 gauge.
We find both to be of value and I'm not finding a reason to choose one over the other when we can keep both in our system.
