Sodium ion batteries don't have the same longevity as LFP in their current form (2-3k cycles vs 4-8k cycles), so they are not really an economical replacement at this point.
Wouldn't batteries used in a home power backup situation be rarely cycling? (unless you completely go off grid as the earlier poster was suggesting)
If the battery is being used to address the duck curve, it cycles approximately every day.
If you can buy twice the capacity for the same price a cell cycles every second day, except on the rare days where you would have had a problem with the old solution.