2nd affection makes a huge difference. I ran a map shortly after it was added and I had 2 squads that use to have equal damage output. I gave second affection to all of the units in the squad and while the one without 2nd affection did fine the squad that got the boost absolutely eviscerated everything in their path.

You also get 2 flower gems for hitting 100% 2nd affection, so there's that as a bonus as well.