I'm starting to remember seeing few spellhances. Though I have no recollection of them performing well (maybe they were just mediocre, or lower dps for me to pay attention).
Also some statements of enhance doing more ST dmg, why would you go spellhance against mostly ST oriented bosses, where AoE isn't a big part. Even then, why pick shaman over some other DPS, when it only brings DPS to raid.