First off this client already had one 12K inverter. Hence the older model on the very right side. So it's pointless to go 15K. This client is 100% off grid.
He Powers up his house, a workshop , and another small house all off this one system.
Well price would play a big factor. As it's cheaper to buy 48v 100ah packs. Which weights little over 100 lb . I would hate to lift a 300 lb battery if they made 48v at 280ah packs.
The smart BMS actually balances batteries pretty good. it will communicate with each other pack. Now each battery bank is actually in sets of nine to a bus bar which is another key factor of having your bank balanced better. Each battery has a double plate so there is no resistant carryover for terminal stacking since there's no terminal stacking.
The BMS cell balancer will work while it's discharging, idling and charging unlike other batteries that can only do one setting( normally just charging) You could change it in the program if you're only preferred one or 2 settings. One of the nice features of the program is you can import your daily hour usage to a spreadsheet.
Had a client with 20 batteries for over 3 years with no balancing issues with the same model of batteries.