I think folks are talking about two different issues here, and it can get very confusing that way
I think the MS2012 Magnum is a 100 amp charger/inverter that also has a separate output breaker for branch circuits.
From playing with our new MS2000, I can tell you that there about a billion different ways to configure things, and examples you have been told are some of them.
The comments about the charger not transitioning to float properly have to do with how they are sensing and controlling that transition. It can be an issue based an a couple of things that are configured. It will only be an issue if:
You are using "return amps", or "SOC" settings to trigger the transition
You have the Magnum ARC remote to get all the options, so you can make those settings.
You DO NOT have the BMK battery monitor installed.
In return amps or SOC, the charger looks at the amps going (allegedly) to the battery. If there is no monitor kit installed, it does a very rough calculation of the amps to the battery based on the AC amps into the charger section. First off, it is a rough estimate to be sure. Secondarily, and what is being talked about, is that if you have the frig running, the charger will not know the power is going to a load instead of the batteries and will stay in absorption to long, or forever, whichever comes first.
If you have the battery monitor kit, it runs on a shunt and measures the actual amps to the battery, so it does not matter what is running or how long it runs. It will still get the correct reading and transition properly.
The other issue concerning the generator, it think is referring to much bigger loads than a 12v frig will take. I don't think 60 watts to a frig is going to overload any generator and short the power to the batteries. It surely isn't going overtax a 100 amp charger.
The solar should take care of itself. If there is not enough solar to run the van and charge batteries, it won't do it, and if you are shore power, the solar (if it setup correctly) is just along for the ride.
I may be missing something, but I think it can all be taken care of pretty easily.