Okay, here's my personal take on Spell Haste.
(22% beneficial spell haste at level 70.... still pretty good).
Daluda's Mending (Qvic gloves FTW!)
2.4s cast time with (25%) and cleric spell haste (10%)
2.8s cast time with only Spell Haste V aug(15%) and cleric spell haste
Yoppa's Mending
2.5s with Goad and cleric buff
2.8s with Spell Haste V and cleric buff
Basically, one-third of a second (.4s off Daluda's) is shaved off from the shammy spell that needs Spell Haste the most -- the spam heal.
So, for a very cheap 180 crystals, enterprising shammies can get much quicker quick heals. The Aug is only 15%, while the Goad is 25% (23.7 for Yoppa's). Having just broken into Tacvi with my guild, I have yet to get any item with a spell haste which replaces 25%.
25% now -- 2.4s is hard to beat
IF shammies (and other healers) were made aware of it.