Shadow;
I'm sure he's very correct in what he's doing. It sounds as if he's quite possibly using a circuit as a protective device that allows him to isolate the batteries from each other within the charging circuit.
Something of that sort would be a good for people who have invested money in 12V systems. Not sure how much money could be made from it. Ghurd could help you with that his dump controller works day in / day out. He's quickly about to be come the next dozenaire.
He has placed his circuit schematic on his website, so if anyone doesn't want to purchase the kit, and has the spare parts lying around they can certainly build one up.
DavidHK did his with SMDs
However, if you build one and have the time to place a schematic up here we would all have a chance to look at how nice it is.
OR build one up and let us know how it does.
Cheers;
Bruce S