I can certainly relate to that. I struggled for months trying to get my stack of 8 EG4 Lifepower4 batteries to charge evenly while hooked up to a pair of EG4 EX6500. I got so frustrated with EG4's inability to properly support the unit, I did the upgrade program and now have a single EG4 6000xp in service, and the other one as a spare. The batteries seem to balance a lot better now, I think that might have something to do with the firmware upgrade I did. I still am not out of the woods though as I know my system is not optimized. The thing that bothers the heck out of me with this new inverter is that I want to be able to set the charge amperage manually and the unit wants to determine it from what it sees from BMS and it seems to have a lot of problems talking to my batteries. I had upgraded my eight batteries with the upgrade dongle and thought I had done a good job, but my unit only sees 5 batteries. I never had the correct cable to hook my batteries up to a PC. Signature Solar is sending me one, but it literally takes them two weeks to process and internal order and ship anything. I'll confirm battery firmware once the cable arrives.
