I don't think that Andy (off grid garage) likes the BMS that comes with the kits.
I thought about your comment Tim, had to go back and re-watch Andy's Seplos vids.
Andy comments early in the vid that the Seplos'BMS 'can communicate with several different Inverters' (user selectable) although at that time he also says 'I don't know why, but the BMS can talk to the Inverter for some reason'.
I realize in Andy's case, he built his own batteries and was very hands-on with his parameter settings, going so far as to test what these settings should be in the first place, and then setting up his system based on his findings.
For most of us, though, we don't use the BMS to set the control of the battery charging/discharging, we do this with the inverter settings, and we rely on the BMS more as ack-up protection in the event of a run-away-cell or failure of the inverter to limit charge/discharge correctly, and to control cell balancing.
Going back to the video, Andy's beef with the Seplos seemed to be that they preset values for their BMS that he didn't agree with.
For ETC and others on the forum, they may not share Andy's view on the Seplos BMS or how it needs to be configured to work with their inverters.
Something to investigate first before making the (sizable) investment in a Seplos kit for sure. I believe from following you on the forum that like myself we are happier to source our own (lower cost) parts for DIY batteries, including a BMS that suits us, rather than the Seplos option.
Still, Seplos is an entry-path to DIY rack batteries for many I suspect, one that removes most of the guess-work on what they will need to put a complete functional battery together.