From what I read, it's not the overcharging or the charging that is the issue, it's the cutoff voltage at which a lifepo might be harmed being a higher threshold than a lead acid battery, so you have to have a BMS for the lifepo which increases the cost and can cause the ups system to miscalculate runtime as it may cut off when it thinks it has 10% remaining.

But if there is a hack to recalibrate them, then great. I'll do some searching for it now as I have two little bms's that need batteries.