It's funny because back in WoTLK if you were under 800 haste rating, you were doing it wrong. I had easily over 1k and could outheal significantly better geared healers simply because Chain Heal was inb4 anything they could cast. What the OP said in his guide was haste is important if your below 916 rating (this is what gets you the extra proc on RT, EL, and HR).
However once you hit 916, it immediately becomes the least desired stat. I would even go so far as to say 916 is the "soft cap" for haste for a resto sham. Does this mean you are fail if you have 1200 haste? no. But does it mean if you have 950 haste, does it make more sense to chant and gem for int, certainly so. I have tested the numbers out on my level 85 shaman in normal 85's and have found it true that haste is fairly useless once you hit that soft cap.
Thanks for the very informative guide. I found a couple of things that I had intuitively figured out but couldn't put into words when explaining it to a guildie.