Sorcadin leveling question, 5/5 or 6/4?

[samcifer]

Extra attack is useful for when you want to go nova, as it allows you two chances to smite without having to spend sorcery points (you can always spend sorcery points for quickening a weapon cantrip, but meh...). PAM is a poor pick for sorcadins.

But it's not really that much of a loss of dmg over haste, right? only about a 3 pt loss on average and doesn't require concentration, which is a plus in that respect.

I thought one of the main selling points of a sorcadin was more slots to smite with.

I could do 1d10 + 5 (STR) + 10 (GWM) + smite (average of 8 on a lv. 1 slot) for 28 x 2, then 1d4 + 5 +10 + 8 for 25, giving me 81 dmg during a single turn and that's not counting higher spell slots used or bonuses from a magic weapon. Then I can do an additional 10 dmg. from my racial ability for 91 dmg or more. That's really good dmg. right?