Common misconception, SotF does
NOT give more throughput. BF is about the only fight it can be competitive, but by no means superior. I would say both are OK choices for BF, but I would recommend Incarnation to most Druids, as it is more flexible and far more forgiving on mana. I honestly see no reason to swap to SotF for this one fight, Incarnation is clearly stronger across all of BRF (I don't see that changing in HFC either), and it is better to get used to sticking with it.
Blast furnace is the only fight in BRF where AOE pulses of damage line up enough with the SM+WG CD. It is the rare exception. Been saying this all tier, and the statistics bear it out.
Once again, here are the rankings for Incarnation in BRF, and it dominates (and on BF, has 6/10 top ranks):
https://www.warcraftlogs.com/ranking...ec=Restoration