Seems some people are looking at this at face value.
I got the RK 2 pretty cheap, it's recourse group haste is 24 seconds shorter than Celerity which is 16 min unfocused.
Celerity = 50% haste 185 mana per cast. for whole group (i know some may not need haste but humor me) total is 1116 mana and its a total cast time of 48 seconds not counting refresh. (and could be more if your hitting pets with it)
RK 2 of this spell is 858 mana, hits whole group in a 6.5 sec casting time (great for if in battle already) and hits your pet with its big buff at the same time. Less mana, less time wasted and hits up to 12 if all have pets with pet affinity.
According to Lucy, rk 1 recourse is 10 min max, rk 12 min and rank 3 is 14 min max. I have tested and my armor focus doesn't effect this, but my rk 2 is 15:36 over 12 min on Lucy so i assume AA do have an affect, or it was changed. Either way, 858 mana for a group haste is good enough for me and my mana pool wouldnt be affected much by it.
And a PS to an earlier post. Group will resist it if they already have shammy haste anyways. that just means no need to cast it every few min.