It is really early, but the first heroic logs are starting to populate in for Jin'rokh, Horridon, Tortos and Megaera. Here is how it now looks.
25H - 39.8% behind
10H - 59.8% behind
As far as raid representation, in 10 man, Shaman representation from Normal to Heroic dropped 15%. In 25 man, Shaman representation dropped 20% from Normal to Heroic.
Although these are early numbers, they are really alarming because
(1) It appears the output gap actually gets higher in heroic modes, which seems to invalidate the argument that the nature of Shaman mastery will make us better on harder fights.
(2) 2 of the 4 fights that early logs are dominated by (Jin'rokh and Megaera) are as favorable for Resto Shaman as any fights this tier. When logs from fights that are extremely bad for Shaman that are later in the tier start to trickle in, the gap may even get worse.
(3) Raid representation is starting to drop in all formats, which indicates that Resto Shaman are being benched or are rerolling.