Herea a link I found for a blue sea acr $65,definately considering for next season.easy installhttp://www.marine-electronics-unlimited ... k+ACR.html
The CL-Series BatteryLink™ ACR connected into your boat’s electrical system provides automatic control for charging dual battery banks.
I guess it all boils down to what one wants the system to do and what you think is reliable.
#3-old age CRS-I don't want to have to remember to turn off the charger after a day of charging or to put the charger on the day before a trip.
Used to be "dry-charge" batteries available. Just add the electrolite and you had a fully charged battery. Good for emergencies since shelf-life was infinite. Don't know if these are still available.
I drove off one day and forgot to unplug the on-board charger . Luckily I caught it before I got a few feet. I could just see the looks going down the road dragging an extension cord.