Yeah, haste makes the fight go the same way, just faster, which can be huge on some fights where bosses do certain mechanics based on time in the fight. However, more spell damage will also make the fight go faster and I'm not sure at what point the two stats are equal.

Assuming all stats stay the same and you just add haste, nothing really changes except the speed of the fight. On the other hand, additional spell damage will decrease the length of the fight as well but with the added bonuse of more damage/mana.

According to WoWHead's weight scale which I believe is directly from Elitist Jerks, elemental shaman should weigh thier stats as follows:

Damage = 100
Crit = 78
Haste = 62
Mana Regen = 30
Int = 25
Hit = 5

Which if my math serves me well means they equate 1.61 haste to 1 damage and therefore your answer is no, you shouldn't give up 60 damage for 50 haste, it would have to be around 97 haste to even be equal.

Edit: And grats on the pants.