As some additional info, I too had thought of getting the battery monitor kit. I figured for $170 it would be a nice addition for minimal work/cost. However when I contacted Magnum, it turned out my Magnum remote ME -RC needed a software upgrade. To get that I'd have to send it to them, not too big of an inconvenience. Then, the tech also asked about my inverter (MS2812) circa 2006. He suspected it needs a newer control board in order to properly work with an upgraded remote and battery monitor. The inverter would need to be removed from the coach, board removed and sent for a new one.
Needless to say that I didn't bother to buy the battery monitor. Someday if I am I Everett I may upgrade the equipment but since everything works well now, I don't see a lot of urgency.
One final thought, the ME-ARC remote is more advanced and combined with the network auto gen-start allows more precise starting protocols, I.e. at specific charge levels say 75%. This is in contrast to the AGS (ME-AGS-S) like the one in my coach where the starting voltages range from 10-12v; not effective as at 12v, which I think is too low, since at that point batteries are discharged to the point that potential harm may be done if repeatedly discharged to that level. Also since on my coach the genset starts from the house batteries, whether there is enough voltage left to start is questionable.
Jeff