This may seem somewhat of a stupid suggestion...however GotN is not a holy talent...or a disc talent...it is a General class talent that should not pop you out of shadow form...
As of now...GotN is a minimal gain of health that i still would use sometimes except when in shadow form its really not mana free due to the fact you have to pop back into shadow form. However with the new buff to GotN scaling better with spell power i would also like to see them make it castable in any form and not remove you from shadowform.
Just a thought....
Chastise is holy spell that pops you out of shadow form...GotN should not...