Yea, we know the problems/complications with pulling 12 outta the middle of 24, that is why many of us are contemplating or are actually shifting to a straight 24v bank with converter...i think its the heat that kills it as it gets/ stays hot from trying to convert down to 12V from 24V all the time.
note: on battery equalization in a 24V system with two 12V batteries, the batteries are like two kids in a trench coat pretending to be a adult 24v battery.
So we have an upper(one you take 24V from) and a lower battery(the one connected to ground/chassis.)
In normal operation the voltage of both batteries should be equal. but when we take 12V loads(current) from the lower battery its voltage drops below that of the upper battery. With no equalization the 24V changing system doesn't see this imbalance and does nothing to fix it.
we add in a equalizer/dual voltage alt to bring the lower battery back up to an equal charge voltage as the upper battery. we do this by sending current back to charge the battery/provide current to loads so the battery it self doesn't need to do it. also if the lower battery voltage is higher than the upper no equalizer/dual alt can do anything about that and you need to either discharge via 12v loads or swap battery locations.
so technically you can treat the lower battery like a load and "charge" it with a Converter/Equalizer. this is why the bussman has the two different hook up methods.