if one uses form of the dragon ii or iii to take the shape of a dragon specified by a lower version of the spell (i or ii), what abilities do you get?
it seems obvious that the size bonuses, natural attacks, and probably fly speed would be tied to the size of the dragon one becomes, but what about the other abilities, like DR, the number of breath weapon uses & it's dmg/range, frightful presenece, resistance vs immunity, etc...
it's nice that the higher-level spells don't exclude one from taking smaller forms, but how much of the spell power do you have to sacrifice when doing so?
i'm inclined to think the breath weapons, at least, match the spell, regardless of the size you assume ... nothing in the spell description says it is tied to the other abilities, and it has its own description, apart from the other abilities.
the elemental body spells are much more clear.