The Goliath powerful build racial trait and the Goliath Barbarian's mountain rage offer a pair of statements that are muddling a character for one of our campaigns, so before I make a ruling I was hoping someone more knowledgeable might shine some light on this issue.
The Powerful Build ability reads, in part:
The beneﬁts of this racial trait stack with the effects of powers, abilities, and spells that change the subject’s size category.
Mountain Rage reads, in part:
However, he does not gain additional beneﬁts on weapon size and grapple checks, since he already has them from his powerful build ability.
Is this line from mountain rage calling itself out as a specific exception to the powerful build abilities (that is, that powerful build "shuts off" whilst the Goliath Barbarian is raging)?
Is mountain rage only saying that the effects of powerful build on grapple checks and weapon size wielding do not apply, but the other effects still do, such as his ability to be one size larger for swallow whole or improved grab?
Is mountain rage's use of the word "additional" calling out its size increasing effect as distinct from, say, Enlarge Person in that it won't increase the character's equipment and other size related abilities as Enlarge Person would, but the effects of the mountain rage don't otherwise subsume the effects of powerful build?