Firefly advocate here. I replaced my 9 year old lifeline bank with fireflies. No complaints and totally happy.
The fact that you can run these batteries
down 80% and do partial recharge is the reason and not killing the battery
is the reason I went for them.
Lifepo looks good, but the numbers dont add up and I am not a fan of a BMS. Sure the BMS will save the bank and potential faults from occurring, but adding that complexity to the ROOT of a tree is not something I want there.